wx2.8.0: wxDC::Blit() and wxMask

[Kövesdi György]

Hi,

My application needs the transparent bitmaps which I tried to use according to 
the documentation. It was good up to the version 2.6.3.

I created the following test code:

        wxMemoryDC mdc;
        wxBitmap bm(100, 100);
        mdc.SelectObject(bm);
        mdc.SetBackground(*wxBLUE_BRUSH);
        mdc.SetPen(wxPen(wxColour(0, 0, 0), 8));
        mdc.Clear();
        mdc.DrawLine(5, 5, 20, 20);

        bm.SetMask(new wxMask(bm, *wxBLUE));

        wxBitmap bm2(100, 100);
        wxMemoryDC dc2;
        dc2.SelectObject(bm2);
        dc2.SetBackground(*wxGREEN_BRUSH);
        dc2.Clear();
        dc2.Blit(0, 0, 100, 100, &mdc, 0, 0, wxCOPY, true);
        dc2.SelectObject(wxNullBitmap);
        mdc.SelectObject(wxNullBitmap);

        (void)new wxStaticBitmap(panel, wxID_ANY, bm2, wxPoint(300, 120));
 
This can be pasted into the file samples/controls/controls.cpp (at line 974 in 
2.8.0, or at line 981 in 2.6.3). In my mind this code must draw a black line 
on a green background, which is the result in 2.6.3. In the version 2.6.8 the 
background is blue, which means the wxDC::Blit() function does not handle the 
transparency.
The transparency seems good in other cases mentioned in the sample sources.

Regards
Gyorgy Kovesdi