fix assert for bitmaps buttons created without bitmap initially

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@48642 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

diff --git a/src/msw/bmpbuttn.cpp b/src/msw/bmpbuttn.cpp
index 83f7efc9d5edfd2c64cbbd278ce0a29274178c14..333ab7a25bff5c4a6a3bdff74c663ab75a4292eb 100644 (file)
--- a/src/msw/bmpbuttn.cpp
+++ b/src/msw/bmpbuttn.cpp
@@ -227,7 +227,7 @@ void wxBitmapButton::OnMouseEnterOrLeave(wxMouseEvent& event)
 void wxBitmapButton::SetBitmapLabel(const wxBitmap& bitmap)
 {
 #if wxUSE_IMAGE
-    if ( !HasFlag(wxBU_AUTODRAW) && !m_disabledSetByUser )
+    if ( !HasFlag(wxBU_AUTODRAW) && !m_disabledSetByUser && bitmap.IsOk() )
     {
         m_bmpDisabled = wxBitmap(bitmap.ConvertToImage().ConvertToGreyscale());
     }