how to custom common controls(draw a transparent progress bar,for example)?

[ezme]

hi,i have learning windows interface design with asm for a few days,
thanks to the friends of this forum,thanks for your help
yet, i have a question about customing common controls.
for example,we can create a transparent static control like this,
when the window CALLBACK function(registered in the window class) received the WM_CTLCOLORSTATIC message,
we get a NULL_BRUSH,put it in eax,and then return.
but how to custom a progress bar or common controls like this?
i searched msdn manual,but had not found msg like WM_CTLCOLORPROGRESSBAR,
and the msg PBS_SETBKCOLOR seems can't deal with this situation
Is it the msg WM_NOTIFY?