store size of WM decorations separately for each TLW, so changes to one do not affect others

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@50165 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

src/gtk/minifram.cpp

@@ -354,6 +354,7 @@ bool wxMiniFrame::Create( wxWindow *parent, wxWindowID id, const wxString &title
 
     // need to reset default size after changing m_gdkDecor
     gtk_window_set_default_size(GTK_WINDOW(m_widget), m_width, m_height);
+    m_decorSize.Set(0, 0);
 
     // don't allow sizing smaller than decorations
     GdkGeometry geom;