Add wxSIZE_FORCE_EVENT and use is from wxSizerItem::SetDimension

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@58526 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

src/gtk/window.cpp

@@ -2540,6 +2540,12 @@ void wxWindowGTK::DoSetSize( int x, int y, int width, int height, int sizeFlags
             event.SetEventObject( this );
             HandleWindowEvent( event );
         }
+    } else 
+    if (sizeFlags & wxSIZE_FORCE_EVENT)
+    {
+        wxSizeEvent event( wxSize(m_width,m_height), GetId() );
+        event.SetEventObject( this );
+        HandleWindowEvent( event );
     }
 }