Merge miscellaneous wxDataViewCtrl-related bug fixes

Make it possible to define custom renderers using text controls reacting to
error presses in at least wxMSW and wxGTK.

Closes https://github.com/wxWidgets/wxWidgets/pull/221

include/wx/msw/textctrl.h

@@ -181,7 +181,10 @@ public:
     void OnSetFocus(wxFocusEvent& event);
 
     // intercept WM_GETDLGCODE
-    virtual WXLRESULT MSWWindowProc(WXUINT nMsg, WXWPARAM wParam, WXLPARAM lParam);
+    virtual bool MSWHandleMessage(WXLRESULT *result,
+                                  WXUINT message,
+                                  WXWPARAM wParam,
+                                  WXLPARAM lParam);
 
     virtual bool MSWShouldPreProcessMessage(WXMSG* pMsg);
     virtual WXDWORD MSWGetStyle(long style, WXDWORD *exstyle) const;

include/wx/msw/window.h

@@ -14,6 +14,8 @@
 
 #include "wx/settings.h"        // solely for wxSystemColour
 
+class WXDLLIMPEXP_FWD_CORE wxButton;
+
 // if this is set to 1, we use deferred window sizing to reduce flicker when
 // resizing complicated window hierarchies, but this can in theory result in
 // different behaviour than the old code so we keep the possibility to use it
@@ -534,6 +536,16 @@ public:
     virtual wxMenu* MSWFindMenuFromHMENU(WXHMENU hMenu);
 #endif // wxUSE_MENUS && !__WXUNIVERSAL__
 
+    // Return the default button for the TLW containing this window or NULL if
+    // none.
+    static wxButton* MSWGetDefaultButtonFor(wxWindow* win);
+
+    // Simulate a click on the given button if it is non-null, enabled and
+    // shown.
+    //
+    // Return true if the button was clicked, false otherwise.
+    static bool MSWClickButtonIfPossible(wxButton* btn);
+
 protected:
     // this allows you to implement standard control borders without
     // repeating the code in different classes that are not derived from