fix generation of events from SetValue() broken in rev 46611

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@48183 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

include/wx/gtk/textctrl.h

@@ -212,7 +212,17 @@ private:
     // encoding
     wxFontEncoding GetTextEncoding() const;
 
+    // returns either m_text or m_buffer depending on whether the control is
+    // single- or multi-line; convenient for the GTK+ functions which work with
+    // both
+    void *GetTextObject() const
+    {
+        return IsMultiLine() ? wx_static_cast(void *, m_buffer)
+                             : wx_static_cast(void *, m_text);
+    }
 
+
+    // the widget used for single line controls
     GtkWidget  *m_text;
 
     bool        m_modified:1;