Last time, I left you with a brief puzzle.
Here are two approaches.
I am not a GDI expert, so there may be even better solutions
out there.
To emphasize the transparency, I'll change the window background
color to the application workspace color.
BOOL WinRegisterClass(WNDCLASS *pwc)
{
pwc->hbrBackground = (HBRUSH)(COLOR_APPWORKSPACE...