Only account for WM frame extents in tlw size if WM supports _NET_FRAME_EXTENTS. Extents cache no longer needed.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@50467 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

include/wx/gtk/taskbarpriv.h

@@ -14,9 +14,6 @@
 
 #include "wx/toplevel.h"
 
-#include <gtk/gtkversion.h>
-#if GTK_CHECK_VERSION(2, 1, 0)
-
 class WXDLLIMPEXP_ADV wxTaskBarIconAreaBase : public wxTopLevelWindow
 {
 public:
@@ -25,8 +22,6 @@ public:
     // Returns true if SYSTRAY protocol is supported by the desktop
     bool IsProtocolSupported();
 
-    virtual bool IsDecorCacheable() const;
-
     wxEvtHandler *m_invokingWindow;
 
 protected:
@@ -35,5 +30,4 @@ protected:
 #endif // wxUSE_MENUS_NATIVE
 };
 
-#endif // GTK_CHECK_VERSION(2, 1, 0)
 #endif // _WX_GTK_TASKBARPRIV_H_