diff --git a/lcl/interfaces/qt/qtwidgets.pas b/lcl/interfaces/qt/qtwidgets.pas
index 228d52c0ab..d98cd4e9d0 100644
--- a/lcl/interfaces/qt/qtwidgets.pas
+++ b/lcl/interfaces/qt/qtwidgets.pas
@@ -2975,7 +2975,8 @@ begin
 
     if not (csCaptureMouse in LCLObject.ControlStyle) and
       (QApplication_mouseButtons() <> QtNoButton) and
-      ((MousePos.X < 0) or (MousePos.Y < 0)) then
+      (((MousePos.X < 0) or (MousePos.Y < 0)) or
+      ((MousePos.X > getWidth) or (MousePos.Y > getHeight))) then
     begin
       if not QWidget_underMouse(Widget) then
         exit;