Cocoa: Treat control-left mouse click same as right mouse click to bring up context menu

lcl/interfaces/cocoa/cocoaconfig.inc

@@ -158,6 +158,13 @@ var
     classicFrame3d: False;
   );
 
+var
+  CocoaConfigMouse: TCocoaConfigMouse = (
+    // False: Control-Left-Click passes straight through
+    // True: Control-Left-Click will become Right Click
+    controlLeftToRightClick: False;
+  );
+
 var
   CocoaConfigNotification: TCocoaConfigNotification = (
     // by default on macOS, Notification is only Presented when the APP is

lcl/interfaces/cocoa/cocoaconfig.pas

@@ -302,6 +302,11 @@ type
     classicFrame3d: Boolean;
   end;
 
+type
+  TCocoaConfigMouse = record
+    controlLeftToRightClick: Boolean;
+  end;
+
 type
   TCocoaConfigNotification = record
     alwaysPresent: Boolean;

lcl/interfaces/cocoa/cocoawscommon.pas

@@ -226,6 +226,7 @@ type
 
 var
   LastMouse: TLastMouseInfo;
+  LastMouseLeftButtonAsRight: Boolean;
 
 function ButtonStateToShiftState(BtnState: PtrUInt): TShiftState;
 begin
@@ -964,6 +965,22 @@ begin
   if AForceAsMouseUp then
     lEventType := NSLeftMouseUp;
 
+  if CocoaConfigMouse.controlLeftToRightClick then begin
+    // treat ctrl+left button as right button
+    if (lEventType = NSLeftMouseDown) and
+       (Event.modifierFlags and NSControlKeyMask <> 0) then
+      LastMouseLeftButtonAsRight := True;
+    if LastMouseLeftButtonAsRight then
+    begin
+      if MButton = 0 then
+        MButton := 1;
+      if Msg.Keys and MK_LBUTTON <> 0 then
+        Msg.Keys := (Msg.Keys or MK_RBUTTON) and not MK_LBUTTON;
+      if lEventType = NSLeftMouseUp then
+        LastMouseLeftButtonAsRight := False;
+    end;
+  end;
+
   Result := Result or (BlockCocoaUpDown and not AOverrideBlock);
   mc := CocoaWidgetSet.ModalCounter;
   case lEventType of