allow using SetFont(wxNullFont) to reset the font as per documented behaviour (#3238)

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/branches/WX_2_8_BRANCH@54664 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

docs/changes.txt

@@ -121,6 +121,7 @@ wxMSW:
 - Compile fix for WinCE in window.cpp (no VkKeyScan in Windows CE).
 - Fix quoting of arguments passed to wxExecute(char **) (Brian Ravnsgaard Riis).
 - Support disabling items before adding them to the menu (Christian Walther).
+- Allow to call SetFont(wxNullFont) to reset the font to default.
 
 wxGTK:
 

src/msw/window.cpp

@@ -811,7 +811,11 @@ bool wxWindowMSW::SetFont(const wxFont& font)
     HWND hWnd = GetHwnd();
     if ( hWnd != 0 )
     {
-        WXHANDLE hFont = m_font.GetResourceHandle();
+        // note the use of GetFont() instead of m_font: our own font could have
+        // just been reset and in this case we need to change the font used by
+        // the native window to the default for this class, i.e. exactly what
+        // GetFont() returns
+        WXHANDLE hFont = GetFont().GetResourceHandle();
 
         wxASSERT_MSG( hFont, wxT("should have valid font") );