Ownerdraw buttons (2)

I have an other question about owner draw buttons.
In my main window everything works fine, but when I use ownerdraw buttons in a dialogbox, I have a huge bug.
at first everything is fine, but when I move the dialobox with its body of the screen, or I put an other window on top, the buttons are gone, shouldn't windows end a WM_DRAWITEM whenever the buttons need to be repainted?

or am I forgetting a function that call the WM_DRAWITEM?

here's the code for WM_DRAWITEM

Code:

case WM_DRAWITEM :
lpdis = (LPDRAWITEMSTRUCT) lParam; 
hdcMem = CreateCompatibleDC(lpdis->hDC); 
switch(lpdis->CtlID)
{
case IDC_PREV:
SelectObject(hdcMem, hbmprev);
StretchBlt(lpdis->hDC, lpdis->rcItem.left,lpdis->rcItem.top, 
lpdis->rcItem.right - lpdis->rcItem.left, 
lpdis->rcItem.bottom - lpdis->rcItem.top, 
hdcMem,0, 0,47,50,SRCCOPY);
return 0;
......
}

here is also a pic if I didn't make myself clear.
the first one is after I put an other window in front of the dialogbox, the second one is the original:

Please edit your source code to change the StretchBlt() line into multiple shorter lines, so that the post is not two screen widths wide, which makes the post easily readable for everyone without scrolling.

Who's still using 800x600??

Me.

your wish is my command
done

but no one knows the answer, or even a thought what the problem could be ?

Or is there a ay that I can keep the dilogbox in memory so that it doesn't need a repain?

Or is there a message that is send to the dlg that notifies a repaint (not specific the buttons) like WM_PAINT, so I can do a several sendmessage WM_DRAWITEM with the specific id of the button. Could this work (I'm going to try with a WM_PAINT but I have a feeling that I will end up in a loop)

Problem solved.
guess what, I forgot to delete the hdc

Code:

DeleteDC(hdcMem);

Originally posted by BMJ
Who's still using 800x600??

About 1/3 of Internet surfers use 800x600, and about 1/2 use 1024x768. I personally use 1152x864. His post was not quite two screens wide, but anyone running less than 1600x1200 was forced to scroll to read it. It's too bad the code tags do not work like a table, so that the text outside of the code remains confined to the viewable screen, even if the code within the table is twice the width.

Yea well... I figured you guys would be better than "most" people though