diff --git a/lcl/interfaces/gtk2/gtk2winapi.inc b/lcl/interfaces/gtk2/gtk2winapi.inc
index 557afa9dff..7f674ee348 100644
--- a/lcl/interfaces/gtk2/gtk2winapi.inc
+++ b/lcl/interfaces/gtk2/gtk2winapi.inc
@@ -6141,7 +6141,6 @@ function TGtk2WidgetSet.GetWindowRect(Handle: hwnd; var ARect: TRect): Integer;
 var
   Widget: PGTKWidget;
   GRect: TGdkRectangle;
-  R: TRect;
   P: TPoint;
 begin
   Result := 0; // error
@@ -6149,14 +6148,14 @@ begin
   begin
     Widget := {%H-}PGtkWidget(Handle);
 
-    if GTK_IS_WINDOW(Widget) and Assigned(Widget^.window) then
+    if GTK_IS_WINDOW(Widget) and Assigned(Widget^.window)
+    and GTK_WIDGET_VISIBLE(Widget) then
     begin
       gdk_window_get_origin(Widget^.window, @ARect.Left, @ARect.Top);
       gdk_window_get_size(Widget^.window, @ARect.Right, @ARect.Bottom);
       P := GetWidgetOrigin(Widget);
       gdk_window_get_frame_extents(Widget^.window, @GRect);
-      R := RectFromGdkRect(GRect);
-      ARect := Bounds(P.X,P.Y,R.Right-R.Left,R.Bottom-R.Top);
+      ARect := Bounds(P.X,P.Y,GRect.width,GRect.height);
       // writeln('Frame extents are: ',dbgs(R),' ARECT=',dbgs(AREct));
       Result := 1; // success
       exit;
diff --git a/lcl/interfaces/gtk2/gtk2wsforms.pp b/lcl/interfaces/gtk2/gtk2wsforms.pp
index 19d2b2acf9..3e7abbcb43 100644
--- a/lcl/interfaces/gtk2/gtk2wsforms.pp
+++ b/lcl/interfaces/gtk2/gtk2wsforms.pp
@@ -353,6 +353,7 @@ var
   WindowType: TGtkWindowType;
   ACustomForm: TCustomForm;
   AResizable: gint;
+  Allocation: TGtkAllocation;
 begin
   // Start of old CreateForm method
   ACustomForm := TCustomForm(AWinControl);
@@ -443,6 +444,12 @@ begin
   if not (csDesigning in AWinControl.ComponentState) then
     WidgetInfo^.UserData := Pointer(1);
 
+  Allocation.X := AParams.X;
+  Allocation.Y := AParams.Y;
+  Allocation.Width := AParams.Width;
+  Allocation.Height := AParams.Height;
+  gtk_widget_size_allocate(P, @Allocation);
+
   {$IFDEF DebugLCLComponents}
   DebugGtkWidgets.MarkCreated(P, dbgsName(AWinControl));
   {$ENDIF}