From db2d5e907e2bab3b0aa571ce1d718f64b3b58bc4 Mon Sep 17 00:00:00 2001
From: ondrej <ondrej@lazarus-ide.org>
Date: Mon, 23 May 2016 14:48:02 +0000
Subject: [PATCH] qt: add support for WM_NCHITTEST=HTTRANSPARENT windows.

git-svn-id: trunk@52359 -
---
 lcl/interfaces/qt/qtwidgets.pas | 24 ++++++++++++++++++------
 1 file changed, 18 insertions(+), 6 deletions(-)

diff --git a/lcl/interfaces/qt/qtwidgets.pas b/lcl/interfaces/qt/qtwidgets.pas
index 7edc38d8d5..d9d083c731 100644
--- a/lcl/interfaces/qt/qtwidgets.pas
+++ b/lcl/interfaces/qt/qtwidgets.pas
@@ -3521,12 +3521,13 @@ end;
 function TQtWidget.SlotMouse(Sender: QObjectH; Event: QEventH): Boolean; cdecl;
 var
   Msg: TLMMouse;
-  MousePos: TQtPoint;
   MButton: QTMouseButton;
   Modifiers: QtKeyboardModifiers;
   SaveWidget: QWidgetH;
   LazButton: Byte;
   LazPos: TPoint;
+  TrgHandle: TQtWidget;
+  TrgControl: TWinControl;
 begin
   {$ifdef VerboseQt}
     WriteLn('TQtWidget.SlotMouse');
@@ -3534,6 +3535,19 @@ begin
 
   Result := False; // allow qt to handle message
 
+  TrgHandle := Self;
+  TrgControl := LCLObject;
+  CheckTransparentWindow(TLCLIntfHandle(TrgHandle), TrgControl);
+  if (TrgHandle=nil) or (TrgControl=nil) then
+  begin
+    Exit;
+  end else
+  if (TrgHandle<>Self) then
+  begin
+    Result := TQtWidget(TrgHandle).SlotMouse(Sender, Event);
+    Exit;
+  end;
+
   if not CanSendLCLMessage then
     exit(True);
 
@@ -3545,17 +3559,15 @@ begin
 
   FillChar(Msg{%H-}, SizeOf(Msg), #0);
   
-  MousePos := QMouseEvent_pos(QMouseEventH(Event))^;
-  OffsetMousePos(@MousePos);
+  LazPos := LCLObject.ScreenToClient(Mouse.CursorPos);
 
   Modifiers := QInputEvent_modifiers(QInputEventH(Event));
   Msg.Keys := QtKeyModifiersToKeyState(Modifiers, False, nil);
 
-  Msg.XPos := SmallInt(MousePos.X);
-  Msg.YPos := SmallInt(MousePos.Y);
+  Msg.XPos := SmallInt(LazPos.X);
+  Msg.YPos := SmallInt(LazPos.Y);
   
   MButton := QMouseEvent_Button(QMouseEventH(Event));
-  LazPos := Point(MousePos.X, MousePos.Y);
   Msg.Keys := Msg.Keys or QtButtonsToLCLButtons(MButton);
   case MButton of
     QtLeftButton: LazButton := 1;