Invalidate best size when the bitmap or bitmap position changes. Add GetBitmapMargins

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@63595 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

src/osx/button_osx.cpp

@@ -104,11 +104,13 @@ void wxButton::DoSetBitmap(const wxBitmap& bitmap, State which)
         if ( bi )
             bi->SetPressedBitmap(bitmap);
     }
+    InvalidateBestSize();
 }
 
 void wxButton::DoSetBitmapPosition(wxDirection dir)
 {
     m_peer->SetBitmapPosition(dir);
+    InvalidateBestSize();
 }
 
 wxWindow *wxButton::SetDefault()