Add an accessor for GtkToolbar widget of wxToolBar.

This can be used to customize the toolbar beyond the capabilities of wx API.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@78461 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

include/wx/gtk/toolbar.h

@@ -69,6 +69,8 @@ public:
     // implementation from now on
     // --------------------------
 
+    GtkToolbar* GTKGetToolbar() const { return m_toolbar; }
+
 protected:
     // choose the default border for this window
     virtual wxBorder GetDefaultBorder() const wxOVERRIDE { return wxBORDER_DEFAULT; }