Add wxWindow::CreateUsingMSWClass() helper function

This method allows to use the Windows class to use for the window being
created instead of always using "wxWindow" or "wxWindowNR".

This can be useful to make it possible to handle some windows specially from
outside the application, e.g. use specific class names for accessibility
purposes as will be done by the next commit.

src/msw/window.cpp

@@ -481,12 +481,13 @@ const wxChar *wxWindowMSW::GetMSWClassName() const
 }
 
 // real construction (Init() must have been called before!)
-bool wxWindowMSW::Create(wxWindow *parent,
-                         wxWindowID id,
-                         const wxPoint& pos,
-                         const wxSize& size,
-                         long style,
-                         const wxString& name)
+bool wxWindowMSW::CreateUsingMSWClass(const wxChar* classname,
+                                      wxWindow *parent,
+                                      wxWindowID id,
+                                      const wxPoint& pos,
+                                      const wxSize& size,
+                                      long style,
+                                      const wxString& name)
 {
     wxCHECK_MSG( parent, false, wxT("can't create wxWindow without parent") );
 
@@ -512,7 +513,7 @@ bool wxWindowMSW::Create(wxWindow *parent,
         msflags |= WS_VISIBLE;
     }
 
-    if ( !MSWCreate(GetMSWClassName(), NULL, pos, size, msflags, exstyle) )
+    if ( !MSWCreate(classname, NULL, pos, size, msflags, exstyle) )
         return false;
 
     InheritAttributes();