diff -ura dolphin-18.08.3.orig/src/dolphinmainwindow.cpp dolphin-18.08.3.new/src/dolphinmainwindow.cpp
--- dolphin-18.08.3.orig/src/dolphinmainwindow.cpp	2018-11-09 14:38:47.556089139 -0500
+++ dolphin-18.08.3.new/src/dolphinmainwindow.cpp	2018-11-09 14:45:24.522392872 -0500
@@ -273,7 +273,7 @@
     const int selectedUrlsCount = m_tabWidget->currentTabPage()->selectedItemsCount();
 
     QAction* compareFilesAction = actionCollection()->action(QStringLiteral("compare_files"));
-    if (selectedUrlsCount == 2) {
+    if (selectedUrlsCount == 2 || selectedUrlsCount == 3) {
         compareFilesAction->setEnabled(isKompareInstalled());
     } else {
         compareFilesAction->setEnabled(false);
@@ -705,7 +705,7 @@
 void DolphinMainWindow::compareFiles()
 {
     const KFileItemList items = m_tabWidget->currentTabPage()->selectedItems();
-    if (items.count() != 2) {
+    if (items.count() != 2 && items.count() != 3) {
         // The action is disabled in this case, but it could have been triggered
         // via D-Bus, see https://bugs.kde.org/show_bug.cgi?id=325517
         return;
@@ -714,12 +714,18 @@
     QUrl urlA = items.at(0).url();
     QUrl urlB = items.at(1).url();
 
-    QString command(QStringLiteral("kompare -c \""));
+    QString command(QStringLiteral("meld \""));
     command.append(urlA.toDisplayString(QUrl::PreferLocalFile));
     command.append("\" \"");
     command.append(urlB.toDisplayString(QUrl::PreferLocalFile));
     command.append('\"');
-    KRun::runCommand(command, QStringLiteral("Kompare"), QStringLiteral("kompare"), this);
+    if (items.count() == 3) {
+        QUrl urlC = items.at(2).url();
+        command.append(" \"");
+        command.append(urlC.toDisplayString(QUrl::PreferLocalFile));
+        command.append('\"');
+    }
+    KRun::runCommand(command, QStringLiteral("Meld"), QStringLiteral("meld"), this);
 }
 
 void DolphinMainWindow::toggleShowMenuBar()
@@ -1181,7 +1187,7 @@
 
     QAction* compareFiles = actionCollection()->addAction(QStringLiteral("compare_files"));
     compareFiles->setText(i18nc("@action:inmenu Tools", "Compare Files"));
-    compareFiles->setIcon(QIcon::fromTheme(QStringLiteral("kompare")));
+    compareFiles->setIcon(QIcon::fromTheme(QStringLiteral("meld")));
     compareFiles->setEnabled(false);
     connect(compareFiles, &QAction::triggered, this, &DolphinMainWindow::compareFiles);
 
@@ -1576,7 +1582,7 @@
     if (!initialized) {
         // TODO: maybe replace this approach later by using a menu
         // plugin like kdiff3plugin.cpp
-        installed = !QStandardPaths::findExecutable(QStringLiteral("kompare")).isEmpty();
+        installed = !QStandardPaths::findExecutable(QStringLiteral("meld")).isEmpty();
         initialized = true;
     }
     return installed;