Don't accept focus in the dummy main generic spin control window.

This window is only used as a container for the sub-windows and shouldn't
accept focus, trying to set it to it doesn't work anyhow (see #12004).

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@64230 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

include/wx/generic/spinctlg.h

@@ -92,6 +92,10 @@ public:
     void OnTextEnter(wxCommandEvent& event);
     void OnTextChar(wxKeyEvent& event);
 
+    // this window itself is used only as a container for its sub windows so it
+    // shouldn't accept the focus at all
+    virtual bool AcceptsFocus() const { return false; }
+
     friend class wxSpinCtrlTextGeneric;
 
 protected: