summarylogtreecommitdiffstats
path: root/0025-Add-KDE-integration-to-Firefox-toolkit-parts.patch
blob: 1b113382f7c48971d380f974d90ef7af70b73bdb (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
905
906
907
908
909
910
911
912
913
914
915
916
917
918
919
920
921
922
923
924
925
926
927
928
929
930
931
932
933
934
935
936
937
938
939
940
941
942
943
944
945
946
947
948
949
950
951
952
953
954
955
956
957
958
959
960
961
962
963
964
965
966
967
968
969
970
971
972
973
974
975
976
977
978
979
980
981
982
983
984
985
986
987
988
989
990
991
992
993
994
995
996
997
998
999
1000
1001
1002
1003
1004
1005
1006
1007
1008
1009
1010
1011
1012
1013
1014
1015
1016
1017
1018
1019
1020
1021
1022
1023
1024
1025
1026
1027
1028
1029
1030
1031
1032
1033
1034
1035
1036
1037
1038
1039
1040
1041
1042
1043
1044
1045
1046
1047
1048
1049
1050
1051
1052
1053
1054
1055
1056
1057
1058
1059
1060
1061
1062
1063
1064
1065
1066
1067
1068
1069
1070
1071
1072
1073
1074
1075
1076
1077
1078
1079
1080
1081
1082
1083
1084
1085
1086
1087
1088
1089
1090
1091
1092
1093
1094
1095
1096
1097
1098
1099
1100
1101
1102
1103
1104
1105
1106
1107
1108
1109
1110
1111
1112
1113
1114
1115
1116
1117
1118
1119
1120
1121
1122
1123
1124
1125
1126
1127
1128
1129
1130
1131
1132
1133
1134
1135
1136
1137
1138
1139
1140
1141
1142
1143
1144
1145
1146
1147
1148
1149
1150
1151
1152
1153
1154
1155
1156
1157
1158
1159
1160
1161
1162
1163
1164
1165
1166
1167
1168
1169
1170
1171
1172
1173
1174
1175
1176
1177
1178
1179
1180
1181
1182
1183
1184
1185
1186
1187
1188
1189
1190
1191
1192
1193
1194
1195
1196
1197
1198
1199
1200
1201
1202
1203
1204
1205
1206
1207
1208
1209
1210
1211
1212
1213
1214
1215
1216
1217
1218
1219
1220
1221
1222
1223
1224
1225
1226
1227
1228
1229
1230
1231
1232
1233
1234
1235
1236
1237
1238
1239
1240
1241
1242
1243
1244
1245
1246
1247
1248
1249
1250
1251
1252
1253
1254
1255
1256
1257
1258
1259
1260
1261
1262
1263
1264
1265
1266
1267
1268
1269
1270
1271
1272
1273
1274
1275
1276
1277
1278
1279
1280
1281
1282
1283
1284
1285
1286
1287
1288
1289
1290
1291
1292
1293
1294
1295
1296
1297
1298
1299
1300
1301
1302
1303
1304
1305
1306
1307
1308
1309
1310
1311
1312
1313
1314
1315
1316
1317
1318
1319
1320
1321
1322
1323
1324
1325
1326
1327
1328
1329
1330
1331
1332
1333
1334
1335
1336
1337
1338
1339
1340
1341
1342
1343
1344
1345
1346
1347
1348
1349
1350
1351
1352
1353
1354
1355
1356
1357
1358
1359
1360
1361
1362
1363
1364
1365
1366
1367
1368
1369
1370
1371
1372
1373
1374
1375
1376
1377
1378
1379
1380
1381
1382
1383
1384
1385
1386
1387
1388
1389
1390
1391
1392
1393
1394
1395
1396
1397
1398
1399
1400
1401
1402
1403
1404
1405
1406
1407
1408
1409
1410
1411
1412
1413
1414
1415
1416
1417
1418
1419
1420
1421
1422
From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
From: Wolfgang Rosenauer <wolfgang@rosenauer.org>
Date: Tue, 8 Aug 2023 16:13:48 +0300
Subject: [PATCH] Add KDE integration to Firefox (toolkit parts)
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

Bug: https://bugzilla.mozilla.org/show_bug.cgi?id=140751
Bug: https://bugzilla.suse.com/show_bug.cgi?id=170055

EDIT: Björn Bidar: Removed handling for obsolete special files

Co-authored-by: Wolfgang Rosenauer <wolfgang@rosenauer.org>
Co-authored-by: Lubos Lunak <lunak@suse.com>
Co-authored-by: Björn Bidar <bjorn.bidar@thaodan.de>
---
 modules/libpref/Preferences.cpp               |   1 +
 modules/libpref/moz.build                     |   4 +
 python/mozbuild/mozpack/chrome/flags.py       |   1 +
 python/mozbuild/mozpack/chrome/manifest.py    |   1 +
 toolkit/components/downloads/moz.build        |   4 +
 .../mozapps/downloads/HelperAppDlg.sys.mjs    |  70 +++--
 .../unixproxy/nsUnixSystemProxySettings.cpp   |  29 ++
 toolkit/xre/moz.build                         |   2 +
 toolkit/xre/nsKDEUtils.cpp                    | 286 ++++++++++++++++++
 toolkit/xre/nsKDEUtils.h                      |  53 ++++
 uriloader/exthandler/HandlerServiceParent.cpp |   6 +-
 uriloader/exthandler/moz.build                |   3 +
 .../exthandler/unix/nsCommonRegistry.cpp      |  42 +++
 uriloader/exthandler/unix/nsCommonRegistry.h  |  28 ++
 uriloader/exthandler/unix/nsKDERegistry.cpp   |  75 +++++
 uriloader/exthandler/unix/nsKDERegistry.h     |  35 +++
 uriloader/exthandler/unix/nsMIMEInfoUnix.cpp  |  28 +-
 .../exthandler/unix/nsOSHelperAppService.cpp  |  10 +-
 widget/gtk/moz.build                          |   1 +
 widget/gtk/nsFilePicker.cpp                   | 230 +++++++++++++-
 widget/gtk/nsFilePicker.h                     |   6 +
 xpcom/components/ManifestParser.cpp           |  10 +
 xpcom/components/moz.build                    |   1 +
 xpcom/io/nsLocalFileUnix.cpp                  |  20 +-
 24 files changed, 910 insertions(+), 36 deletions(-)
 create mode 100644 toolkit/xre/nsKDEUtils.cpp
 create mode 100644 toolkit/xre/nsKDEUtils.h
 create mode 100644 uriloader/exthandler/unix/nsCommonRegistry.cpp
 create mode 100644 uriloader/exthandler/unix/nsCommonRegistry.h
 create mode 100644 uriloader/exthandler/unix/nsKDERegistry.cpp
 create mode 100644 uriloader/exthandler/unix/nsKDERegistry.h

diff --git a/modules/libpref/Preferences.cpp b/modules/libpref/Preferences.cpp
index 7860eaa60179d6e5e0952ad0ec75e38b37d8d1b7..a8358199720719f2d5aaff91e30307b752ca0d85 100644
--- a/modules/libpref/Preferences.cpp
+++ b/modules/libpref/Preferences.cpp
@@ -96,6 +96,7 @@
 #ifdef MOZ_BACKGROUNDTASKS
 #  include "mozilla/BackgroundTasks.h"
 #endif
+#include "nsKDEUtils.h"
 
 #ifdef DEBUG
 #  include <map>
diff --git a/modules/libpref/moz.build b/modules/libpref/moz.build
index 3e835d422cfdfb07410b01e834bee2973ae30c57..ce58aec8ef07acf971290174b9ee5c172b1fdccd 100644
--- a/modules/libpref/moz.build
+++ b/modules/libpref/moz.build
@@ -126,6 +126,10 @@ UNIFIED_SOURCES += [
     "SharedPrefMap.cpp",
 ]
 
+LOCAL_INCLUDES += [
+    '/toolkit/xre'
+]
+
 gen_all_tuple = tuple(gen_h + gen_cpp + gen_rs)
 
 GeneratedFile(
diff --git a/python/mozbuild/mozpack/chrome/flags.py b/python/mozbuild/mozpack/chrome/flags.py
index 6b096c862aaac5e02d9d7dacda42d9321d5e89cc..2b46d9294b93fda17117e9c84b240c52f96c9b74 100644
--- a/python/mozbuild/mozpack/chrome/flags.py
+++ b/python/mozbuild/mozpack/chrome/flags.py
@@ -234,6 +234,7 @@ class Flags(OrderedDict):
         "tablet": Flag,
         "process": StringFlag,
         "backgroundtask": StringFlag,
+        "desktop": StringFlag,
     }
     RE = re.compile(r"([!<>=]+)")
 
diff --git a/python/mozbuild/mozpack/chrome/manifest.py b/python/mozbuild/mozpack/chrome/manifest.py
index 14c11d4c1daa8cbb03abf3cd2e1a7b60a981abc8..41b9969e7277fa2400f299863c83145342cd7b43 100644
--- a/python/mozbuild/mozpack/chrome/manifest.py
+++ b/python/mozbuild/mozpack/chrome/manifest.py
@@ -43,6 +43,7 @@ class ManifestEntry(object):
         "process",
         "contentaccessible",
         "backgroundtask",
+        "desktop",
     ]
 
     def __init__(self, base, *flags):
diff --git a/toolkit/components/downloads/moz.build b/toolkit/components/downloads/moz.build
index 3818e8c0db1ed3cfc068d89b18b1fe2f1bf750a9..b70986db811191952919531cfb79e04b801491a2 100644
--- a/toolkit/components/downloads/moz.build
+++ b/toolkit/components/downloads/moz.build
@@ -51,5 +51,9 @@ if CONFIG["MOZ_PLACES"]:
 
 FINAL_LIBRARY = "xul"
 
+LOCAL_INCLUDES += [
+    '/toolkit/xre'
+]
+
 with Files("**"):
     BUG_COMPONENT = ("Toolkit", "Downloads API")
diff --git a/toolkit/mozapps/downloads/HelperAppDlg.sys.mjs b/toolkit/mozapps/downloads/HelperAppDlg.sys.mjs
index 66f77d38e4ed7b3802303194e8df675a5db81272..f8839c446683620d6df6c6eb2ea0a0ca3549af95 100644
--- a/toolkit/mozapps/downloads/HelperAppDlg.sys.mjs
+++ b/toolkit/mozapps/downloads/HelperAppDlg.sys.mjs
@@ -1246,26 +1246,56 @@ nsUnknownContentTypeDialog.prototype = {
         this.chosenApp = params.handlerApp;
       }
     } else if ("@mozilla.org/applicationchooser;1" in Cc) {
-      var nsIApplicationChooser = Ci.nsIApplicationChooser;
-      var appChooser = Cc["@mozilla.org/applicationchooser;1"].createInstance(
-        nsIApplicationChooser
-      );
-      appChooser.init(
-        this.mDialog,
-        this.dialogElement("strings").getString("chooseAppFilePickerTitle")
-      );
-      var contentTypeDialogObj = this;
-      let appChooserCallback = function appChooserCallback_done(aResult) {
-        if (aResult) {
-          contentTypeDialogObj.chosenApp = aResult.QueryInterface(
-            Ci.nsILocalHandlerApp
-          );
-        }
-        contentTypeDialogObj.finishChooseApp();
-      };
-      appChooser.open(this.mLauncher.MIMEInfo.MIMEType, appChooserCallback);
-      // The finishChooseApp is called from appChooserCallback
-      return;
+      // handle the KDE case which is implemented in the filepicker
+      // therefore falling back to Gtk2 like behaviour if KDE is running
+      // FIXME this should be better handled in the nsIApplicationChooser
+      // interface
+      var env = Components.classes["@mozilla.org/process/environment;1"]
+                          .getService(Components.interfaces.nsIEnvironment);
+      if (env.get('KDE_FULL_SESSION') == "true")
+      {
+        var nsIFilePicker = Ci.nsIFilePicker;
+        var fp = Cc["@mozilla.org/filepicker;1"]
+                    .createInstance(nsIFilePicker);
+        fp.init(this.mDialog,
+                this.dialogElement("strings").getString("chooseAppFilePickerTitle"),
+                nsIFilePicker.modeOpen);
+
+        fp.appendFilters(nsIFilePicker.filterApps);
+
+        fp.open(aResult => {
+          if (aResult == nsIFilePicker.returnOK && fp.file) {
+            // Remember the file they chose to run.
+            var localHandlerApp =
+              Cc["@mozilla.org/uriloader/local-handler-app;1"].
+                         createInstance(Ci.nsILocalHandlerApp);
+            localHandlerApp.executable = fp.file;
+            this.chosenApp = localHandlerApp;
+          }
+          this.finishChooseApp();
+        });
+      } else {
+        var nsIApplicationChooser = Ci.nsIApplicationChooser;
+        var appChooser = Cc["@mozilla.org/applicationchooser;1"].createInstance(
+          nsIApplicationChooser
+        );
+        appChooser.init(
+          this.mDialog,
+          this.dialogElement("strings").getString("chooseAppFilePickerTitle")
+        );
+        var contentTypeDialogObj = this;
+        let appChooserCallback = function appChooserCallback_done(aResult) {
+          if (aResult) {
+            contentTypeDialogObj.chosenApp = aResult.QueryInterface(
+              Ci.nsILocalHandlerApp
+            );
+          }
+          contentTypeDialogObj.finishChooseApp();
+        };
+        appChooser.open(this.mLauncher.MIMEInfo.MIMEType, appChooserCallback);
+        // The finishChooseApp is called from appChooserCallback
+        return;
+      }
     } else {
       var nsIFilePicker = Ci.nsIFilePicker;
       var fp = Cc["@mozilla.org/filepicker;1"].createInstance(nsIFilePicker);
diff --git a/toolkit/system/unixproxy/nsUnixSystemProxySettings.cpp b/toolkit/system/unixproxy/nsUnixSystemProxySettings.cpp
index 185dc1e22a903cec95b212d1713dddf764b9b198..bdb4ed6f9f86583d02dd80278f858d064584f82a 100644
--- a/toolkit/system/unixproxy/nsUnixSystemProxySettings.cpp
+++ b/toolkit/system/unixproxy/nsUnixSystemProxySettings.cpp
@@ -16,6 +16,8 @@
 #include "nsISupportsPrimitives.h"
 #include "nsIGSettingsService.h"
 #include "nsReadableUtils.h"
+#include "nsPrintfCString.h"
+#include "nsKDEUtils.h"
 
 using namespace mozilla;
 
@@ -39,6 +41,8 @@ class nsUnixSystemProxySettings final : public nsISystemProxySettings {
                                  nsACString& aResult);
   nsresult SetProxyResultFromGSettings(const char* aKeyBase, const char* aType,
                                        nsACString& aResult);
+  nsresult GetProxyFromKDE(const nsACString& aScheme, const nsACString& aHost,
+                           PRInt32 aPort, nsACString& aResult);
 };
 
 NS_IMPL_ISUPPORTS(nsUnixSystemProxySettings, nsISystemProxySettings)
@@ -397,6 +401,9 @@ nsresult nsUnixSystemProxySettings::GetProxyForURI(const nsACString& aSpec,
                                                    const nsACString& aHost,
                                                    const int32_t aPort,
                                                    nsACString& aResult) {
+  if (nsKDEUtils::kdeSupport())
+    return GetProxyFromKDE(aScheme, aHost, aPort, aResult);
+
   if (mProxySettings) {
     nsresult rv = GetProxyFromGSettings(aScheme, aHost, aPort, aResult);
     if (NS_SUCCEEDED(rv)) return rv;
@@ -405,6 +412,28 @@ nsresult nsUnixSystemProxySettings::GetProxyForURI(const nsACString& aSpec,
   return GetProxyFromEnvironment(aScheme, aHost, aPort, aResult);
 }
 
+nsresult nsUnixSystemProxySettings::GetProxyFromKDE(const nsACString& aScheme,
+                                                    const nsACString& aHost,
+                                                    PRInt32 aPort,
+                                                    nsACString& aResult) {
+  nsAutoCString url;
+  url = aScheme;
+  url += "://";
+  url += aHost;
+  if (aPort >= 0) {
+    url += ":";
+    url += nsPrintfCString("%d", aPort);
+  }
+  nsTArray<nsCString> command;
+  command.AppendElement("GETPROXY"_ns);
+  command.AppendElement(url);
+  nsTArray<nsCString> result;
+  if (!nsKDEUtils::command(command, &result) || result.Length() != 1)
+    return NS_ERROR_FAILURE;
+  aResult = result[0];
+  return NS_OK;
+}
+
 NS_IMPL_COMPONENT_FACTORY(nsUnixSystemProxySettings) {
   auto result = MakeRefPtr<nsUnixSystemProxySettings>();
   result->Init();
diff --git a/toolkit/xre/moz.build b/toolkit/xre/moz.build
index 9a76d1f580c08fafe6b3ab53669cb2ee6c289d12..80416ff1b4edeba2d90c934f2e8a5a519aaed041 100644
--- a/toolkit/xre/moz.build
+++ b/toolkit/xre/moz.build
@@ -96,7 +96,9 @@ elif CONFIG["MOZ_WIDGET_TOOLKIT"] == "uikit":
         "UIKitDirProvider.mm",
     ]
 elif CONFIG["MOZ_WIDGET_TOOLKIT"] == "gtk":
+    EXPORTS += ['nsKDEUtils.h']
     UNIFIED_SOURCES += [
+        "nsKDEUtils.cpp",
         "nsNativeAppSupportUnix.cpp",
     ]
     CXXFLAGS += CONFIG["MOZ_X11_SM_CFLAGS"]
diff --git a/toolkit/xre/nsKDEUtils.cpp b/toolkit/xre/nsKDEUtils.cpp
new file mode 100644
index 0000000000000000000000000000000000000000..ca0266b4868811e4afe2db4a1d9e7663ffd2a1ce
--- /dev/null
+++ b/toolkit/xre/nsKDEUtils.cpp
@@ -0,0 +1,286 @@
+/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "nsKDEUtils.h"
+#include "nsIWidget.h"
+#include "nsISupportsPrimitives.h"
+#include "nsIMutableArray.h"
+#include "nsComponentManagerUtils.h"
+#include "nsArrayUtils.h"
+
+#include <gtk/gtk.h>
+
+#include <limits.h>
+#include <stdio.h>
+#include <sys/wait.h>
+#include <sys/resource.h>
+#include <unistd.h>
+#include <X11/Xlib.h>
+// copied from X11/X.h as a hack since for an unknown
+// reason it's not picked up from X11/X.h
+//#ifndef None
+//#  define None 0L /* universal null resource or null atom */
+//#endif
+
+// #define DEBUG_KDE
+#ifdef DEBUG_KDE
+#  define KMOZILLAHELPER "kmozillahelper"
+#else
+// not need for lib64, it's a binary
+#  define KMOZILLAHELPER "/usr/lib/mozilla/kmozillahelper"
+#endif
+
+#define KMOZILLAHELPER_VERSION 6
+#define MAKE_STR2(n) #n
+#define MAKE_STR(n) MAKE_STR2(n)
+
+static bool getKdeSession() {
+  if (PR_GetEnv("KDE_FULL_SESSION")) {
+    return true;
+  }
+  return false;
+}
+
+static bool getKdeSupport() {
+  nsTArray<nsCString> command;
+  command.AppendElement("CHECK"_ns);
+  command.AppendElement("KMOZILLAHELPER_VERSION"_ns);
+  bool kde = nsKDEUtils::command(command);
+#ifdef DEBUG_KDE
+  fprintf(stderr, "KDE RUNNING %d\n", kde);
+#endif
+  return kde;
+}
+
+nsKDEUtils::nsKDEUtils() : commandFile(NULL), replyFile(NULL) {}
+
+nsKDEUtils::~nsKDEUtils() {
+  //    closeHelper(); not actually useful, exiting will close the fd too
+}
+
+nsKDEUtils* nsKDEUtils::self() {
+  static nsKDEUtils s;
+  return &s;
+}
+
+static bool helperRunning = false;
+static bool helperFailed = false;
+
+bool nsKDEUtils::kdeSession() {
+  static bool session = getKdeSession();
+  return session;
+}
+
+bool nsKDEUtils::kdeSupport() {
+  static bool support = kdeSession() && getKdeSupport();
+  return support && helperRunning;
+}
+
+struct nsKDECommandData {
+  FILE* file;
+  nsTArray<nsCString>* output;
+  GMainLoop* loop;
+  bool success;
+};
+
+static gboolean kdeReadFunc(GIOChannel*, GIOCondition, gpointer data) {
+  nsKDECommandData* p = static_cast<nsKDECommandData*>(data);
+  char buf[8192];  // TODO big enough
+  bool command_done = false;
+  bool command_failed = false;
+  while (!command_done && !command_failed &&
+         fgets(buf, 8192, p->file) !=
+             NULL) {  // TODO what if the kernel splits a line into two chunks?
+                      // #ifdef DEBUG_KDE
+    //         fprintf( stderr, "READ: %s %d\n", buf, feof( p->file ));
+    // #endif
+    if (char* eol = strchr(buf, '\n')) *eol = '\0';
+    command_done = (strcmp(buf, "\\1") == 0);
+    command_failed = (strcmp(buf, "\\0") == 0);
+    nsAutoCString line(buf);
+    line.ReplaceSubstring("\\n", "\n");
+    line.ReplaceSubstring(
+        "\\"
+        "\\",
+        "\\");  //  \\ -> \ , i.e. unescape
+    if (p->output && !(command_done || command_failed))
+      p->output->AppendElement(nsCString(buf));  // TODO utf8?
+  }
+  bool quit = false;
+  if (feof(p->file) || command_failed) {
+    quit = true;
+    p->success = false;
+  }
+  if (command_done) {  // reading one reply finished
+    quit = true;
+    p->success = true;
+  }
+  if (quit) {
+    if (p->loop) g_main_loop_quit(p->loop);
+    return FALSE;
+  }
+  return TRUE;
+}
+
+bool nsKDEUtils::command(const nsTArray<nsCString>& command,
+                         nsTArray<nsCString>* output) {
+  return self()->internalCommand(command, NULL, false, output);
+}
+
+bool nsKDEUtils::command(nsIArray* command, nsIArray** output) {
+  nsTArray<nsCString> in;
+  PRUint32 length;
+  command->GetLength(&length);
+  for (PRUint32 i = 0; i < length; i++) {
+    nsCOMPtr<nsISupportsCString> str = do_QueryElementAt(command, i);
+    if (str) {
+      nsAutoCString s;
+      str->GetData(s);
+      in.AppendElement(s);
+    }
+  }
+
+  nsTArray<nsCString> out;
+  bool ret = self()->internalCommand(in, NULL, false, &out);
+
+  if (!output) return ret;
+
+  nsCOMPtr<nsIMutableArray> result = do_CreateInstance(NS_ARRAY_CONTRACTID);
+  if (!result) return false;
+
+  for (PRUint32 i = 0; i < out.Length(); i++) {
+    nsCOMPtr<nsISupportsCString> rstr =
+        do_CreateInstance(NS_SUPPORTS_CSTRING_CONTRACTID);
+    if (!rstr) return false;
+
+    rstr->SetData(out[i]);
+    result->AppendElement(rstr);
+  }
+
+  NS_ADDREF(*output = result);
+  return ret;
+}
+
+bool nsKDEUtils::commandBlockUi(const nsTArray<nsCString>& command,
+                                GtkWindow* parent,
+                                nsTArray<nsCString>* output) {
+  return self()->internalCommand(command, parent, true, output);
+}
+
+bool nsKDEUtils::internalCommand(const nsTArray<nsCString>& command,
+                                 GtkWindow* parent, bool blockUi,
+                                 nsTArray<nsCString>* output) {
+  if (!startHelper()) return false;
+  feedCommand(command);
+  // do not store the data in 'this' but in extra structure, just in case there
+  // is reentrancy (can there be? the event loop is re-entered)
+  nsKDECommandData data;
+  data.file = replyFile;
+  data.output = output;
+  data.success = false;
+  if (blockUi) {
+    data.loop = g_main_loop_new(NULL, FALSE);
+    GtkWidget* window = gtk_window_new(GTK_WINDOW_TOPLEVEL);
+    if (parent && gtk_window_get_group(parent))
+      gtk_window_group_add_window(gtk_window_get_group(parent),
+                                  GTK_WINDOW(window));
+    gtk_widget_realize(window);
+    gtk_widget_set_sensitive(window, TRUE);
+    gtk_grab_add(window);
+    GIOChannel* channel = g_io_channel_unix_new(fileno(data.file));
+    g_io_add_watch(channel,
+                   static_cast<GIOCondition>(G_IO_IN | G_IO_ERR | G_IO_HUP),
+                   kdeReadFunc, &data);
+    g_io_channel_unref(channel);
+    g_main_loop_run(data.loop);
+    g_main_loop_unref(data.loop);
+    gtk_grab_remove(window);
+    gtk_widget_destroy(window);
+  } else {
+    data.loop = NULL;
+    while (kdeReadFunc(NULL, static_cast<GIOCondition>(0), &data))
+      ;
+  }
+  return data.success;
+}
+
+bool nsKDEUtils::startHelper() {
+  if (helperRunning) return true;
+  if (helperFailed) return false;
+  helperFailed = true;
+  int fdcommand[2];
+  int fdreply[2];
+  if (pipe(fdcommand) < 0) return false;
+  if (pipe(fdreply) < 0) {
+    close(fdcommand[0]);
+    close(fdcommand[1]);
+    return false;
+  }
+  char* args[2] = {const_cast<char*>(KMOZILLAHELPER), NULL};
+  switch (fork()) {
+    case -1: {
+      close(fdcommand[0]);
+      close(fdcommand[1]);
+      close(fdreply[0]);
+      close(fdreply[1]);
+      return false;
+    }
+    case 0:  // child
+    {
+      if (dup2(fdcommand[0], STDIN_FILENO) < 0) _exit(1);
+      if (dup2(fdreply[1], STDOUT_FILENO) < 0) _exit(1);
+      int maxfd = 1024;  // close all other fds
+      struct rlimit rl;
+      if (getrlimit(RLIMIT_NOFILE, &rl) == 0) maxfd = rl.rlim_max;
+      for (int i = 3; i < maxfd; ++i) close(i);
+#ifdef DEBUG_KDE
+      execvp(KMOZILLAHELPER, args);
+#else
+      execv(KMOZILLAHELPER, args);
+#endif
+      _exit(1);  // failed
+    }
+    default:  // parent
+    {
+      commandFile = fdopen(fdcommand[1], "w");
+      replyFile = fdopen(fdreply[0], "r");
+      close(fdcommand[0]);
+      close(fdreply[1]);
+      if (commandFile == NULL || replyFile == NULL) {
+        closeHelper();
+        return false;
+      }
+      // ok, helper ready, getKdeRunning() will check if it works
+    }
+  }
+  helperFailed = false;
+  helperRunning = true;
+  return true;
+}
+
+void nsKDEUtils::closeHelper() {
+  if (commandFile != NULL)
+    fclose(commandFile);  // this will also make the helper quit
+  if (replyFile != NULL) fclose(replyFile);
+  helperRunning = false;
+}
+
+void nsKDEUtils::feedCommand(const nsTArray<nsCString>& command) {
+  for (int i = 0; i < command.Length(); ++i) {
+    nsCString line = command[i];
+    line.ReplaceSubstring("\\",
+                          "\\"
+                          "\\");  // \ -> \\ , i.e. escape
+    line.ReplaceSubstring("\n", "\\n");
+#ifdef DEBUG_KDE
+    fprintf(stderr, "COMM: %s\n", line.get());
+#endif
+    fputs(line.get(), commandFile);
+    fputs("\n", commandFile);
+  }
+  fputs("\\E\n",
+        commandFile);  // done as \E, so it cannot happen in normal data
+  fflush(commandFile);
+}
diff --git a/toolkit/xre/nsKDEUtils.h b/toolkit/xre/nsKDEUtils.h
new file mode 100644
index 0000000000000000000000000000000000000000..7fa6eb8e83b32c8e2c62a0035d253e06e135e3d2
--- /dev/null
+++ b/toolkit/xre/nsKDEUtils.h
@@ -0,0 +1,53 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef nsKDEUtils_h__
+#define nsKDEUtils_h__
+
+#include "nsString.h"
+#include "nsTArray.h"
+#include <stdio.h>
+
+typedef struct _GtkWindow GtkWindow;
+
+class nsIArray;
+
+class NS_EXPORT nsKDEUtils {
+ public:
+  /* Returns true if running inside a KDE session (regardless of whether there
+     is KDE support available for Firefox). This should be used e.g. when
+     determining dialog button order but not for code that requires the KDE
+     support. */
+  static bool kdeSession();
+  /* Returns true if running inside a KDE session and KDE support is available
+     for Firefox. This should be used everywhere where the external helper is
+     needed. */
+  static bool kdeSupport();
+  /* Executes the given helper command, returns true if helper returned success.
+   */
+  static bool command(const nsTArray<nsCString>& command,
+                      nsTArray<nsCString>* output = NULL);
+  static bool command(nsIArray* command, nsIArray** output = NULL);
+  /* Like command(), but additionally blocks the parent widget like if there was
+     a modal dialog shown and enters the event loop (i.e. there are still paint
+     updates, this is for commands that take long). */
+  static bool commandBlockUi(const nsTArray<nsCString>& command,
+                             GtkWindow* parent,
+                             nsTArray<nsCString>* output = NULL);
+
+ private:
+  nsKDEUtils();
+  ~nsKDEUtils();
+  static nsKDEUtils* self();
+  bool startHelper();
+  void closeHelper();
+  void feedCommand(const nsTArray<nsCString>& command);
+  bool internalCommand(const nsTArray<nsCString>& command, GtkWindow* parent,
+                       bool isParent, nsTArray<nsCString>* output);
+  FILE* commandFile;
+  FILE* replyFile;
+};
+
+#endif  // nsKDEUtils
diff --git a/uriloader/exthandler/HandlerServiceParent.cpp b/uriloader/exthandler/HandlerServiceParent.cpp
index ab77657dd5f378af0955c43ef958a8abea620134..18b4d85560699bbc3c69b82ee91dfb5cbe700e7b 100644
--- a/uriloader/exthandler/HandlerServiceParent.cpp
+++ b/uriloader/exthandler/HandlerServiceParent.cpp
@@ -18,7 +18,7 @@
 #include "nsComponentManagerUtils.h"
 #include "nsServiceManagerUtils.h"
 #ifdef MOZ_WIDGET_GTK
-#  include "unix/nsGNOMERegistry.h"
+#  include "unix/nsCommonRegistry.h"
 #endif
 
 using mozilla::dom::ContentHandlerService;
@@ -310,8 +310,8 @@ mozilla::ipc::IPCResult HandlerServiceParent::RecvExistsForProtocolOS(
   }
 #ifdef MOZ_WIDGET_GTK
   // Check the GNOME registry for a protocol handler
-  *aHandlerExists =
-      nsGNOMERegistry::HandlerExists(PromiseFlatCString(aProtocolScheme).get());
+  *aHandlerExists = nsCommonRegistry::HandlerExists(
+      PromiseFlatCString(aProtocolScheme).get());
 #else
   *aHandlerExists = false;
 #endif
diff --git a/uriloader/exthandler/moz.build b/uriloader/exthandler/moz.build
index cb96c690a69a87a95dc28cc4903cd84718c324af..164c06c8d186f7af445fa5bd5c08757b1c89e7fd 100644
--- a/uriloader/exthandler/moz.build
+++ b/uriloader/exthandler/moz.build
@@ -86,7 +86,9 @@ else:
 
 if CONFIG["MOZ_WIDGET_TOOLKIT"] == "gtk":
     UNIFIED_SOURCES += [
+        "unix/nsCommonRegistry.cpp",
         "unix/nsGNOMERegistry.cpp",
+        "unix/nsKDERegistry.cpp",
         "unix/nsMIMEInfoUnix.cpp",
     ]
 elif CONFIG["MOZ_WIDGET_TOOLKIT"] == "android":
@@ -134,6 +136,7 @@ LOCAL_INCLUDES += [
     "/dom/ipc",
     "/netwerk/base",
     "/netwerk/protocol/http",
+    "/toolkit/xre",
 ]
 
 if CONFIG["MOZ_ENABLE_DBUS"]:
diff --git a/uriloader/exthandler/unix/nsCommonRegistry.cpp b/uriloader/exthandler/unix/nsCommonRegistry.cpp
new file mode 100644
index 0000000000000000000000000000000000000000..3371a756e2c240bfe5fe31ef0ee9c393368dab60
--- /dev/null
+++ b/uriloader/exthandler/unix/nsCommonRegistry.cpp
@@ -0,0 +1,42 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "nsCommonRegistry.h"
+
+#include "nsGNOMERegistry.h"
+#include "nsKDERegistry.h"
+#include "nsString.h"
+#include "nsKDEUtils.h"
+
+/* static */ bool nsCommonRegistry::HandlerExists(const char* aProtocolScheme) {
+  if (nsKDEUtils::kdeSupport())
+    return nsKDERegistry::HandlerExists(aProtocolScheme);
+  return nsGNOMERegistry::HandlerExists(aProtocolScheme);
+}
+
+/* static */ nsresult nsCommonRegistry::LoadURL(nsIURI* aURL) {
+  if (nsKDEUtils::kdeSupport()) return nsKDERegistry::LoadURL(aURL);
+  return nsGNOMERegistry::LoadURL(aURL);
+}
+
+/* static */ void nsCommonRegistry::GetAppDescForScheme(
+    const nsACString& aScheme, nsAString& aDesc) {
+  if (nsKDEUtils::kdeSupport())
+    return nsKDERegistry::GetAppDescForScheme(aScheme, aDesc);
+  return nsGNOMERegistry::GetAppDescForScheme(aScheme, aDesc);
+}
+
+/* static */ already_AddRefed<nsMIMEInfoBase>
+nsCommonRegistry::GetFromExtension(const nsACString& aFileExt) {
+  if (nsKDEUtils::kdeSupport())
+    return nsKDERegistry::GetFromExtension(aFileExt);
+  return nsGNOMERegistry::GetFromExtension(aFileExt);
+}
+
+/* static */ already_AddRefed<nsMIMEInfoBase> nsCommonRegistry::GetFromType(
+    const nsACString& aMIMEType) {
+  if (nsKDEUtils::kdeSupport()) return nsKDERegistry::GetFromType(aMIMEType);
+  return nsGNOMERegistry::GetFromType(aMIMEType);
+}
diff --git a/uriloader/exthandler/unix/nsCommonRegistry.h b/uriloader/exthandler/unix/nsCommonRegistry.h
new file mode 100644
index 0000000000000000000000000000000000000000..075413e2fbb165862956c7753a750bfdfb5d389b
--- /dev/null
+++ b/uriloader/exthandler/unix/nsCommonRegistry.h
@@ -0,0 +1,28 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef nsCommonRegistry_h__
+#define nsCommonRegistry_h__
+
+#include "nsIURI.h"
+#include "nsCOMPtr.h"
+
+class nsMIMEInfoBase;
+
+class nsCommonRegistry {
+ public:
+  static bool HandlerExists(const char* aProtocolScheme);
+
+  static nsresult LoadURL(nsIURI* aURL);
+
+  static void GetAppDescForScheme(const nsACString& aScheme, nsAString& aDesc);
+
+  static already_AddRefed<nsMIMEInfoBase> GetFromExtension(
+      const nsACString& aFileExt);
+
+  static already_AddRefed<nsMIMEInfoBase> GetFromType(
+      const nsACString& aMIMEType);
+};
+
+#endif
diff --git a/uriloader/exthandler/unix/nsKDERegistry.cpp b/uriloader/exthandler/unix/nsKDERegistry.cpp
new file mode 100644
index 0000000000000000000000000000000000000000..082035566f0b82c14f866c2fbed34c0884f27d34
--- /dev/null
+++ b/uriloader/exthandler/unix/nsKDERegistry.cpp
@@ -0,0 +1,75 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "mozilla/StaticPrefs_browser.h"
+#include "nsKDERegistry.h"
+#include "prlink.h"
+#include "prmem.h"
+#include "nsString.h"
+#include "nsMIMEInfoUnix.h"
+#include "nsKDEUtils.h"
+
+/* static */ bool nsKDERegistry::HandlerExists(const char* aProtocolScheme) {
+  nsTArray<nsCString> command;
+  command.AppendElement("HANDLEREXISTS"_ns);
+  command.AppendElement(nsAutoCString(aProtocolScheme));
+  return nsKDEUtils::command(command);
+}
+
+/* static */ nsresult nsKDERegistry::LoadURL(nsIURI* aURL) {
+  nsTArray<nsCString> command;
+  command.AppendElement("OPEN"_ns);
+  nsCString url;
+  aURL->GetSpec(url);
+  command.AppendElement(url);
+  bool rv = nsKDEUtils::command(command);
+  if (!rv) return NS_ERROR_FAILURE;
+
+  return NS_OK;
+}
+
+/* static */ void nsKDERegistry::GetAppDescForScheme(const nsACString& aScheme,
+                                                     nsAString& aDesc) {
+  nsTArray<nsCString> command;
+  command.AppendElement("GETAPPDESCFORSCHEME"_ns);
+  command.AppendElement(aScheme);
+  nsTArray<nsCString> output;
+  if (nsKDEUtils::command(command, &output) && output.Length() == 1)
+    CopyUTF8toUTF16(output[0], aDesc);
+}
+
+/* static */ already_AddRefed<nsMIMEInfoBase> nsKDERegistry::GetFromExtension(
+    const nsACString& aFileExt) {
+  NS_ASSERTION(aFileExt[0] != '.', "aFileExt shouldn't start with a dot");
+  nsTArray<nsCString> command;
+  command.AppendElement("GETFROMEXTENSION"_ns);
+  command.AppendElement(aFileExt);
+  return GetFromHelper(command);
+}
+
+/* static */ already_AddRefed<nsMIMEInfoBase> nsKDERegistry::GetFromType(
+    const nsACString& aMIMEType) {
+  nsTArray<nsCString> command;
+  command.AppendElement("GETFROMTYPE"_ns);
+  command.AppendElement(aMIMEType);
+  return GetFromHelper(command);
+}
+
+/* static */ already_AddRefed<nsMIMEInfoBase> nsKDERegistry::GetFromHelper(
+    const nsTArray<nsCString>& command) {
+  nsTArray<nsCString> output;
+  if (nsKDEUtils::command(command, &output) && output.Length() == 3) {
+    nsCString mimetype = output[0];
+    RefPtr<nsMIMEInfoUnix> mimeInfo = new nsMIMEInfoUnix(mimetype);
+    NS_ENSURE_TRUE(mimeInfo, nullptr);
+    nsCString description = output[1];
+    mimeInfo->SetDescription(NS_ConvertUTF8toUTF16(description));
+    nsCString handlerAppName = output[2];
+    mimeInfo->SetPreferredAction(nsIMIMEInfo::saveToDisk);
+    mimeInfo->SetDefaultDescription(NS_ConvertUTF8toUTF16(handlerAppName));
+    return mimeInfo.forget();
+  }
+  return nullptr;
+}
diff --git a/uriloader/exthandler/unix/nsKDERegistry.h b/uriloader/exthandler/unix/nsKDERegistry.h
new file mode 100644
index 0000000000000000000000000000000000000000..c6a41b331b2b5ead6142171f08d8b8a7872ca516
--- /dev/null
+++ b/uriloader/exthandler/unix/nsKDERegistry.h
@@ -0,0 +1,35 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef nsKDERegistry_h__
+#define nsKDERegistry_h__
+
+#include "nsIURI.h"
+#include "nsCOMPtr.h"
+#include "nsTArray.h"
+
+class nsMIMEInfoBase;
+// class nsAutoCString;
+// class nsCString;
+
+class nsKDERegistry {
+ public:
+  static bool HandlerExists(const char* aProtocolScheme);
+
+  static nsresult LoadURL(nsIURI* aURL);
+
+  static void GetAppDescForScheme(const nsACString& aScheme, nsAString& aDesc);
+
+  static already_AddRefed<nsMIMEInfoBase> GetFromExtension(
+      const nsACString& aFileExt);
+
+  static already_AddRefed<nsMIMEInfoBase> GetFromType(
+      const nsACString& aMIMEType);
+
+ private:
+  static already_AddRefed<nsMIMEInfoBase> GetFromHelper(
+      const nsTArray<nsCString>& command);
+};
+
+#endif  // nsKDERegistry_h__
diff --git a/uriloader/exthandler/unix/nsMIMEInfoUnix.cpp b/uriloader/exthandler/unix/nsMIMEInfoUnix.cpp
index 330c4411597f1a19105601e256a2c3bc71c61780..c96c1f3ca5a05c3b6bce321d7a975aa040865fa8 100644
--- a/uriloader/exthandler/unix/nsMIMEInfoUnix.cpp
+++ b/uriloader/exthandler/unix/nsMIMEInfoUnix.cpp
@@ -5,16 +5,19 @@
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
 #include "nsMIMEInfoUnix.h"
-#include "nsGNOMERegistry.h"
+#include "nsCommonRegistry.h"
 #include "nsIGIOService.h"
 #include "nsNetCID.h"
 #include "nsIIOService.h"
 #ifdef MOZ_ENABLE_DBUS
 #  include "nsDBusHandlerApp.h"
 #endif
+#if defined(XP_UNIX) && !defined(XP_MACOSX)
+#  include "nsKDEUtils.h"
+#endif
 
 nsresult nsMIMEInfoUnix::LoadUriInternal(nsIURI* aURI) {
-  return nsGNOMERegistry::LoadURL(aURI);
+  return nsCommonRegistry::LoadURL(aURI);
 }
 
 NS_IMETHODIMP
@@ -29,15 +32,15 @@ nsMIMEInfoUnix::GetHasDefaultHandler(bool* _retval) {
   *_retval = false;
 
   if (mClass == eProtocolInfo) {
-    *_retval = nsGNOMERegistry::HandlerExists(mSchemeOrType.get());
+    *_retval = nsCommonRegistry::HandlerExists(mSchemeOrType.get());
   } else {
     RefPtr<nsMIMEInfoBase> mimeInfo =
-        nsGNOMERegistry::GetFromType(mSchemeOrType);
+        nsCommonRegistry::GetFromType(mSchemeOrType);
     if (!mimeInfo) {
       nsAutoCString ext;
       nsresult rv = GetPrimaryExtension(ext);
       if (NS_SUCCEEDED(rv)) {
-        mimeInfo = nsGNOMERegistry::GetFromExtension(ext);
+        mimeInfo = nsCommonRegistry::GetFromExtension(ext);
       }
     }
     if (mimeInfo) *_retval = true;
@@ -59,6 +62,21 @@ nsresult nsMIMEInfoUnix::LaunchDefaultWithFile(nsIFile* aFile) {
   nsAutoCString nativePath;
   aFile->GetNativePath(nativePath);
 
+  if (nsKDEUtils::kdeSupport()) {
+    bool supports;
+    if (NS_SUCCEEDED(GetHasDefaultHandler(&supports)) && supports) {
+      nsTArray<nsCString> command;
+      command.AppendElement("OPEN"_ns);
+      command.AppendElement(nativePath);
+      command.AppendElement("MIMETYPE"_ns);
+      command.AppendElement(mSchemeOrType);
+      if (nsKDEUtils::command(command)) return NS_OK;
+    }
+    if (!GetDefaultApplication()) return NS_ERROR_FILE_NOT_FOUND;
+
+    return LaunchWithIProcess(GetDefaultApplication(), nativePath);
+  }
+
   nsCOMPtr<nsIGIOService> giovfs = do_GetService(NS_GIOSERVICE_CONTRACTID);
   if (!giovfs) {
     return NS_ERROR_FAILURE;
diff --git a/uriloader/exthandler/unix/nsOSHelperAppService.cpp b/uriloader/exthandler/unix/nsOSHelperAppService.cpp
index 7f6eaa46f2ee0d5155b83bfb07d8040584935772..f7627e790c47e1ae007b072b4bb47b18de1ae417 100644
--- a/uriloader/exthandler/unix/nsOSHelperAppService.cpp
+++ b/uriloader/exthandler/unix/nsOSHelperAppService.cpp
@@ -10,7 +10,7 @@
 #include "nsOSHelperAppService.h"
 #include "nsMIMEInfoUnix.h"
 #ifdef MOZ_WIDGET_GTK
-#  include "nsGNOMERegistry.h"
+#  include "nsCommonRegistry.h"
 #  ifdef MOZ_BUILD_APP_IS_BROWSER
 #    include "nsIToolkitShellService.h"
 #    include "nsIGNOMEShellService.h"
@@ -1106,7 +1106,7 @@ nsresult nsOSHelperAppService::OSProtocolHandlerExists(
   if (!XRE_IsContentProcess()) {
 #ifdef MOZ_WIDGET_GTK
     // Check the GNOME registry for a protocol handler
-    *aHandlerExists = nsGNOMERegistry::HandlerExists(aProtocolScheme);
+    *aHandlerExists = nsCommonRegistry::HandlerExists(aProtocolScheme);
 #else
     *aHandlerExists = false;
 #endif
@@ -1126,7 +1126,7 @@ nsresult nsOSHelperAppService::OSProtocolHandlerExists(
 NS_IMETHODIMP nsOSHelperAppService::GetApplicationDescription(
     const nsACString& aScheme, nsAString& _retval) {
 #ifdef MOZ_WIDGET_GTK
-  nsGNOMERegistry::GetAppDescForScheme(aScheme, _retval);
+  nsCommonRegistry::GetAppDescForScheme(aScheme, _retval);
   return _retval.IsEmpty() ? NS_ERROR_NOT_AVAILABLE : NS_OK;
 #else
   return NS_ERROR_NOT_AVAILABLE;
@@ -1231,7 +1231,7 @@ already_AddRefed<nsMIMEInfoBase> nsOSHelperAppService::GetFromExtension(
 #ifdef MOZ_WIDGET_GTK
     LOG("Looking in GNOME registry\n");
     RefPtr<nsMIMEInfoBase> gnomeInfo =
-        nsGNOMERegistry::GetFromExtension(aFileExt);
+        nsCommonRegistry::GetFromExtension(aFileExt);
     if (gnomeInfo) {
       LOG("Got MIMEInfo from GNOME registry\n");
       return gnomeInfo.forget();
@@ -1344,7 +1344,7 @@ already_AddRefed<nsMIMEInfoBase> nsOSHelperAppService::GetFromType(
 
 #ifdef MOZ_WIDGET_GTK
   if (handler.IsEmpty()) {
-    RefPtr<nsMIMEInfoBase> gnomeInfo = nsGNOMERegistry::GetFromType(aMIMEType);
+    RefPtr<nsMIMEInfoBase> gnomeInfo = nsCommonRegistry::GetFromType(aMIMEType);
     if (gnomeInfo) {
       LOG("Got MIMEInfo from GNOME registry without extensions; setting them "
           "to %s\n",
diff --git a/widget/gtk/moz.build b/widget/gtk/moz.build
index a6ed6f7c8cd08853f4bf1e25eb658b8fb9a4cbb1..8362e17dee84e45c820ebf99397da914263bc1ef 100644
--- a/widget/gtk/moz.build
+++ b/widget/gtk/moz.build
@@ -161,6 +161,7 @@ LOCAL_INCLUDES += [
     "/layout/xul",
     "/other-licenses/atk-1.0",
     "/third_party/cups/include",
+    "/toolkit/xre",
     "/widget",
     "/widget/headless",
     "/widget/x11",
diff --git a/widget/gtk/nsFilePicker.cpp b/widget/gtk/nsFilePicker.cpp
index d15c44d3a0bde1ae0b3c73ba6f35ace25a1c9a8b..987f23b4ea29ecfa943ce0b1646db669cd40de19 100644
--- a/widget/gtk/nsFilePicker.cpp
+++ b/widget/gtk/nsFilePicker.cpp
@@ -5,6 +5,7 @@
 
 #include <dlfcn.h>
 #include <gtk/gtk.h>
+#include <gdk/gdkx.h>
 #include <sys/types.h>
 #include <sys/stat.h>
 #include <unistd.h>
@@ -30,6 +31,8 @@
 #include "WidgetUtilsGtk.h"
 
 #include "nsFilePicker.h"
+#include "nsKDEUtils.h"
+#include "nsURLHelper.h"
 
 #undef LOG
 #ifdef MOZ_LOGGING
@@ -310,7 +313,8 @@ NS_IMETHODIMP
 nsFilePicker::AppendFilter(const nsAString& aTitle, const nsAString& aFilter) {
   if (aFilter.EqualsLiteral("..apps")) {
     // No platform specific thing we can do here, really....
-    return NS_OK;
+    // Unless it's KDE.
+    if (mMode != modeOpen || !nsKDEUtils::kdeSupport()) return NS_OK;
   }
 
   nsAutoCString filter, name;
@@ -420,6 +424,31 @@ nsFilePicker::Open(nsIFilePickerShownCallback* aCallback) {
   // Can't show two dialogs concurrently with the same filepicker
   if (mRunning) return NS_ERROR_NOT_AVAILABLE;
 
+  // KDE file picker is not handled via callback
+  if (nsKDEUtils::kdeSupport()) {
+    mCallback = aCallback;
+    mRunning = true;
+    NS_ADDREF_THIS();
+    g_idle_add(
+        [](gpointer data) -> gboolean {
+          nsFilePicker* queuedPicker = (nsFilePicker*)data;
+          nsIFilePicker::ResultCode result;
+          queuedPicker->kdeFileDialog(&result);
+          if (queuedPicker->mCallback) {
+            queuedPicker->mCallback->Done(result);
+            queuedPicker->mCallback = nullptr;
+          } else {
+            queuedPicker->mResult = result;
+          }
+          queuedPicker->mRunning = false;
+          NS_RELEASE(queuedPicker);
+          return G_SOURCE_REMOVE;
+        },
+        this);
+
+    return NS_OK;
+  }
+
   NS_ConvertUTF16toUTF8 title(mTitle);
 
   GtkWindow* parent_widget =
@@ -701,6 +730,205 @@ void nsFilePicker::Done(void* file_chooser, gint response) {
   NS_RELEASE_THIS();
 }
 
+nsCString nsFilePicker::kdeMakeFilter(int index) {
+  nsCString buf = mFilters[index];
+  for (PRUint32 i = 0; i < buf.Length(); ++i)
+    if (buf[i] == ';')  // KDE separates just using spaces
+      buf.SetCharAt(' ', i);
+  if (!mFilterNames[index].IsEmpty()) {
+    buf += "|";
+    buf += mFilterNames[index].get();
+  }
+  return buf;
+}
+
+static PRInt32 windowToXid(nsIWidget* widget) {
+  GtkWindow* parent_widget =
+      GTK_WINDOW(widget->GetNativeData(NS_NATIVE_SHELLWIDGET));
+  GdkWindow* gdk_window =
+      gtk_widget_get_window(gtk_widget_get_toplevel(GTK_WIDGET(parent_widget)));
+  return GDK_WINDOW_XID(gdk_window);
+}
+
+NS_IMETHODIMP nsFilePicker::kdeFileDialog(nsIFilePicker::ResultCode* aReturn) {
+  NS_ENSURE_ARG_POINTER(aReturn);
+
+  if (mMode == modeOpen && mFilters.Length() == 1 &&
+      mFilters[0].EqualsLiteral("..apps"))
+    return kdeAppsDialog(aReturn);
+
+  nsCString title;
+  title.Adopt(ToNewUTF8String(mTitle));
+
+  const char* arg = NULL;
+  if (mAllowURLs) {
+    switch (mMode) {
+      case nsIFilePicker::modeOpen:
+      case nsIFilePicker::modeOpenMultiple:
+        arg = "GETOPENURL";
+        break;
+      case nsIFilePicker::modeSave:
+        arg = "GETSAVEURL";
+        break;
+      case nsIFilePicker::modeGetFolder:
+        arg = "GETDIRECTORYURL";
+        break;
+    }
+  } else {
+    switch (mMode) {
+      case nsIFilePicker::modeOpen:
+      case nsIFilePicker::modeOpenMultiple:
+        arg = "GETOPENFILENAME";
+        break;
+      case nsIFilePicker::modeSave:
+        arg = "GETSAVEFILENAME";
+        break;
+      case nsIFilePicker::modeGetFolder:
+        arg = "GETDIRECTORYFILENAME";
+        break;
+    }
+  }
+
+  nsAutoCString directory;
+  if (mDisplayDirectory) {
+    mDisplayDirectory->GetNativePath(directory);
+  } else if (mPrevDisplayDirectory) {
+    mPrevDisplayDirectory->GetNativePath(directory);
+  }
+
+  nsAutoCString startdir;
+  if (!directory.IsEmpty()) {
+    startdir = directory;
+  }
+  if (mMode == nsIFilePicker::modeSave) {
+    if (!startdir.IsEmpty()) {
+      startdir += "/";
+      startdir += ToNewUTF8String(mDefault);
+    } else
+      startdir = ToNewUTF8String(mDefault);
+  }
+
+  nsAutoCString filters;
+  PRInt32 count = mFilters.Length();
+  if (count == 0)  // just in case
+    filters = "*";
+  else {
+    filters = kdeMakeFilter(0);
+    for (PRInt32 i = 1; i < count; ++i) {
+      filters += "\n";
+      filters += kdeMakeFilter(i);
+    }
+  }
+
+  nsTArray<nsCString> command;
+  command.AppendElement(nsAutoCString(arg));
+  command.AppendElement(startdir);
+  if (mMode != nsIFilePicker::modeGetFolder) {
+    command.AppendElement(filters);
+    nsAutoCString selected;
+    selected.AppendInt(mSelectedType);
+    command.AppendElement(selected);
+  }
+  command.AppendElement(title);
+  if (mMode == nsIFilePicker::modeOpenMultiple)
+    command.AppendElement("MULTIPLE"_ns);
+  if (PRInt32 xid = windowToXid(mParentWidget)) {
+    command.AppendElement("PARENT"_ns);
+    nsAutoCString parent;
+    parent.AppendInt(xid);
+    command.AppendElement(parent);
+  }
+
+  nsTArray<nsCString> output;
+  if (nsKDEUtils::commandBlockUi(
+          command,
+          GTK_WINDOW(mParentWidget->GetNativeData(NS_NATIVE_SHELLWIDGET)),
+          &output)) {
+    *aReturn = nsIFilePicker::returnOK;
+    mFiles.Clear();
+    if (mMode != nsIFilePicker::modeGetFolder) {
+      mSelectedType = atoi(output[0].get());
+      output.RemoveElementAt(0);
+    }
+    if (mMode == nsIFilePicker::modeOpenMultiple) {
+      mFileURL.Truncate();
+      PRUint32 count = output.Length();
+      for (PRUint32 i = 0; i < count; ++i) {
+        nsCOMPtr<nsIFile> localfile;
+        nsresult rv = NS_NewNativeLocalFile(output[i], PR_FALSE,
+                                            getter_AddRefs(localfile));
+        if (NS_SUCCEEDED(rv)) mFiles.AppendObject(localfile);
+      }
+    } else {
+      if (output.Length() == 0)
+        mFileURL = nsCString();
+      else if (mAllowURLs)
+        mFileURL = output[0];
+      else  // GetFile() actually requires it to be url even for local files :-/
+      {
+        nsCOMPtr<nsIFile> localfile;
+        nsresult rv = NS_NewNativeLocalFile(output[0], PR_FALSE,
+                                            getter_AddRefs(localfile));
+        if (NS_SUCCEEDED(rv))
+          rv = net_GetURLSpecFromActualFile(localfile, mFileURL);
+      }
+    }
+    // Remember last used directory.
+    nsCOMPtr<nsIFile> file;
+    GetFile(getter_AddRefs(file));
+    if (file) {
+      nsCOMPtr<nsIFile> dir;
+      file->GetParent(getter_AddRefs(dir));
+      nsCOMPtr<nsIFile> localDir(dir);
+      if (localDir) {
+        localDir.swap(mPrevDisplayDirectory);
+      }
+    }
+    if (mMode == nsIFilePicker::modeSave) {
+      nsCOMPtr<nsIFile> file;
+      GetFile(getter_AddRefs(file));
+      if (file) {
+        bool exists = false;
+        file->Exists(&exists);
+        if (exists)  // TODO do overwrite check in the helper app
+          *aReturn = nsIFilePicker::returnReplace;
+      }
+    }
+  } else {
+    *aReturn = nsIFilePicker::returnCancel;
+  }
+  return NS_OK;
+}
+
+NS_IMETHODIMP nsFilePicker::kdeAppsDialog(nsIFilePicker::ResultCode* aReturn) {
+  NS_ENSURE_ARG_POINTER(aReturn);
+
+  nsCString title;
+  title.Adopt(ToNewUTF8String(mTitle));
+
+  nsTArray<nsCString> command;
+  command.AppendElement("APPSDIALOG"_ns);
+  command.AppendElement(title);
+  if (PRInt32 xid = windowToXid(mParentWidget)) {
+    command.AppendElement("PARENT"_ns);
+    nsAutoCString parent;
+    parent.AppendInt(xid);
+    command.AppendElement(parent);
+  }
+
+  nsTArray<nsCString> output;
+  if (nsKDEUtils::commandBlockUi(
+          command,
+          GTK_WINDOW(mParentWidget->GetNativeData(NS_NATIVE_SHELLWIDGET)),
+          &output)) {
+    *aReturn = nsIFilePicker::returnOK;
+    mFileURL = output.Length() > 0 ? output[0] : nsCString();
+  } else {
+    *aReturn = nsIFilePicker::returnCancel;
+  }
+  return NS_OK;
+}
+
 // All below functions available as of GTK 3.20+
 void* nsFilePicker::GtkFileChooserNew(const gchar* title, GtkWindow* parent,
                                       GtkFileChooserAction action,
diff --git a/widget/gtk/nsFilePicker.h b/widget/gtk/nsFilePicker.h
index 7ec93a6694276b3622dbd2d5ba0ececa262b221c..c2571d314c59c3b6d8d70cd65534c9b5818ee86d 100644
--- a/widget/gtk/nsFilePicker.h
+++ b/widget/gtk/nsFilePicker.h
@@ -76,6 +76,12 @@ class nsFilePicker : public nsBaseFilePicker {
  private:
   static nsIFile* mPrevDisplayDirectory;
 
+  bool kdeRunning();
+  bool getKdeRunning();
+  NS_IMETHODIMP kdeFileDialog(nsIFilePicker::ResultCode* aReturn);
+  NS_IMETHODIMP kdeAppsDialog(nsIFilePicker::ResultCode* aReturn);
+  nsCString kdeMakeFilter(int index);
+
   void* GtkFileChooserNew(const gchar* title, GtkWindow* parent,
                           GtkFileChooserAction action,
                           const gchar* accept_label);
diff --git a/xpcom/components/ManifestParser.cpp b/xpcom/components/ManifestParser.cpp
index 88ee06d78db60a84343fd3d23c16e163aead37c3..834d6a2d353cc1bd11916de8a28f5d05a86d9031 100644
--- a/xpcom/components/ManifestParser.cpp
+++ b/xpcom/components/ManifestParser.cpp
@@ -43,6 +43,7 @@
 #include "nsIScriptError.h"
 #include "nsIXULAppInfo.h"
 #include "nsIXULRuntime.h"
+#include "nsKDEUtils.h"
 
 using namespace mozilla;
 
@@ -394,6 +395,7 @@ void ParseManifest(NSLocationType aType, FileLocation& aFile, char* aBuf,
   constexpr auto kOs = u"os"_ns;
   constexpr auto kOsVersion = u"osversion"_ns;
   constexpr auto kABI = u"abi"_ns;
+  constexpr auto kDesktop = u"desktop"_ns;
   constexpr auto kProcess = u"process"_ns;
 #if defined(MOZ_WIDGET_ANDROID)
   constexpr auto kTablet = u"tablet"_ns;
@@ -453,6 +455,7 @@ void ParseManifest(NSLocationType aType, FileLocation& aFile, char* aBuf,
   }
 
   nsAutoString osVersion;
+  nsAutoString desktop;
 #if defined(XP_WIN)
 #  pragma warning(push)
 #  pragma warning(disable : 4996)  // VC12+ deprecates GetVersionEx
@@ -461,14 +464,17 @@ void ParseManifest(NSLocationType aType, FileLocation& aFile, char* aBuf,
     nsTextFormatter::ssprintf(osVersion, u"%ld.%ld", info.dwMajorVersion,
                               info.dwMinorVersion);
   }
+  desktop = u"win"_ns;
 #  pragma warning(pop)
 #elif defined(MOZ_WIDGET_COCOA)
   SInt32 majorVersion = nsCocoaFeatures::macOSVersionMajor();
   SInt32 minorVersion = nsCocoaFeatures::macOSVersionMinor();
   nsTextFormatter::ssprintf(osVersion, u"%ld.%ld", majorVersion, minorVersion);
+  desktop = u"macosx"_ns);
 #elif defined(MOZ_WIDGET_GTK)
   nsTextFormatter::ssprintf(osVersion, u"%ld.%ld", gtk_major_version,
                             gtk_minor_version);
+  desktop = nsKDEUtils::kdeSession() ? u"kde"_ns : u"gnome"_ns;
 #elif defined(MOZ_WIDGET_ANDROID)
   bool isTablet = false;
   if (jni::IsAvailable()) {
@@ -476,6 +482,7 @@ void ParseManifest(NSLocationType aType, FileLocation& aFile, char* aBuf,
     osVersion.Assign(release->ToString());
     isTablet = java::GeckoAppShell::IsTablet();
   }
+  desktop = u"android"_ns;
 #endif
 
   if (XRE_IsContentProcess()) {
@@ -576,6 +583,7 @@ void ParseManifest(NSLocationType aType, FileLocation& aFile, char* aBuf,
                                     : eUnspecified;
 #endif
     int flags = 0;
+    TriState stDesktop = eUnspecified;
 
     while ((token = nsCRT::strtok(whitespace, kWhitespace, &whitespace)) &&
            ok) {
@@ -585,6 +593,7 @@ void ParseManifest(NSLocationType aType, FileLocation& aFile, char* aBuf,
       if (CheckStringFlag(kApplication, wtoken, appID, stApp) ||
           CheckOsFlag(kOs, wtoken, osTarget, stOs) ||
           CheckStringFlag(kABI, wtoken, abi, stABI) ||
+          CheckStringFlag(kDesktop, wtoken, desktop, stDesktop) ||
           CheckStringFlag(kProcess, wtoken, process, stProcess) ||
           CheckVersionFlag(kOsVersion, wtoken, osVersion, stOsVersion) ||
           CheckVersionFlag(kAppVersion, wtoken, appVersion, stAppVersion) ||
@@ -644,6 +653,7 @@ void ParseManifest(NSLocationType aType, FileLocation& aFile, char* aBuf,
 
     if (!ok || stApp == eBad || stAppVersion == eBad ||
         stGeckoVersion == eBad || stOs == eBad || stOsVersion == eBad ||
+        stDesktop == eBad ||
 #ifdef MOZ_WIDGET_ANDROID
         stTablet == eBad ||
 #endif
diff --git a/xpcom/components/moz.build b/xpcom/components/moz.build
index 4a58f46da3f610e9b2f55053939235c7350fedc5..7fb012af861f20932778c59da631f663def2db34 100644
--- a/xpcom/components/moz.build
+++ b/xpcom/components/moz.build
@@ -71,6 +71,7 @@ LOCAL_INCLUDES += [
     "/js/xpconnect/loader",
     "/layout/build",
     "/modules/libjar",
+    "/toolkit/xre",
 ]
 
 if CONFIG["MOZ_WIDGET_TOOLKIT"] == "gtk":
diff --git a/xpcom/io/nsLocalFileUnix.cpp b/xpcom/io/nsLocalFileUnix.cpp
index ae501f40415468c5422c02257e85dd8710a5d01a..190c527916e56ac7aa64233add1d7bc58e8b8ad7 100644
--- a/xpcom/io/nsLocalFileUnix.cpp
+++ b/xpcom/io/nsLocalFileUnix.cpp
@@ -51,6 +51,7 @@
 
 #ifdef MOZ_WIDGET_GTK
 #  include "nsIGIOService.h"
+#  include "nsKDEUtils.h"
 #endif
 
 #ifdef MOZ_WIDGET_COCOA
@@ -2210,10 +2211,18 @@ nsLocalFile::Reveal() {
   }
 
 #ifdef MOZ_WIDGET_GTK
+  nsAutoCString url;
   nsCOMPtr<nsIGIOService> giovfs = do_GetService(NS_GIOSERVICE_CONTRACTID);
-  if (!giovfs) {
-    return NS_ERROR_FAILURE;
+  url = mPath;
+  if (nsKDEUtils::kdeSupport()) {
+    nsTArray<nsCString> command;
+    command.AppendElement("REVEAL"_ns);
+    command.AppendElement(mPath);
+    return nsKDEUtils::command(command) ? NS_OK : NS_ERROR_FAILURE;
   }
+
+  if (!giovfs) return NS_ERROR_FAILURE;
+
   return giovfs->RevealFile(this);
 #elif defined(MOZ_WIDGET_COCOA)
   CFURLRef url;
@@ -2235,6 +2244,13 @@ nsLocalFile::Launch() {
   }
 
 #ifdef MOZ_WIDGET_GTK
+  if (nsKDEUtils::kdeSupport()) {
+    nsTArray<nsCString> command;
+    command.AppendElement("OPEN"_ns);
+    command.AppendElement(mPath);
+    return nsKDEUtils::command(command) ? NS_OK : NS_ERROR_FAILURE;
+  }
+
   nsCOMPtr<nsIGIOService> giovfs = do_GetService(NS_GIOSERVICE_CONTRACTID);
   if (!giovfs) {
     return NS_ERROR_FAILURE;