Allow triggering custom actions via double-clicking a file in the file view

FossilOrigin-Name: 4270974c3f9f7fb166a74a9d76c9db8a24428fe5

src/MainWindow.h

@@ -54,7 +54,7 @@ private:
 	void selectRootDir();
 	void mergeRevision(const QString& defaultRevision);
 	void updateCustomActions();
-
+	void invokeCustomAction(int actionId);
 
 	void fossilBrowse(const QString &fossilUrl);
 	void dragEnterEvent(class QDragEnterEvent *event);