make Set/GetLabel() set and return something (albeit unused) as per the docs, fixes #12350: wxWindow Get/SetLabel non-functional in GTK

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@65374 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

include/wx/gtk/window.h

@@ -45,9 +45,6 @@ public:
     // implement base class (pure) virtual methods
     // -------------------------------------------
 
-    virtual void SetLabel(const wxString& WXUNUSED(label)) { }
-    virtual wxString GetLabel() const { return wxEmptyString; }
-
     virtual bool Destroy();
 
     virtual void Raise();
@@ -114,6 +111,10 @@ public:
     void SetDoubleBuffered(bool on);
     virtual bool IsDoubleBuffered() const;
 
+    // SetLabel(), which does nothing in wxWindow
+    virtual void SetLabel(const wxString& label) { m_gtkLabel = label; }
+    virtual wxString GetLabel() const            { return m_gtkLabel; }
+
     // implementation
     // --------------
 
@@ -242,6 +243,9 @@ public:
     GtkWidget           *m_widget;          // mostly the widget seen by the rest of GTK
     GtkWidget           *m_wxwindow;        // mostly the client area as per wxWidgets
     
+    // label for use with GetLabelSetLabel
+    wxString             m_gtkLabel;
+    
     // return true if the window is of a standard (i.e. not wxWidgets') class
     bool IsOfStandardClass() const { return m_wxwindow == NULL; }