use wxBoxSizer in wxPickerBase instead of doing the layout manually + other picker controls fixes (patch 1513042)

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@39846 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

include/wx/gtk/fontpicker.h

@@ -60,8 +60,6 @@ public:     // used by the GTK callback only
     void SetNativeFontInfo(const gchar *gtkdescription)
         { m_selectedFont.SetNativeFontInfo(wxString::FromAscii(gtkdescription)); }
 
-    wxWindow *m_topParent;
-
 private:
     DECLARE_DYNAMIC_CLASS(wxFontButton)
 };