An application sends a BM_GETIMAGE message to retrieve a handle to the image (icon or bitmap) associated with the button.
BM_GETIMAGE
wParam = (WPARAM) fImageType; // image-type flag
lParam = 0; // not used, must be zero
IMAGE_BITMAP
IMAGE_ICON
The return value is a handle to the image, if any; otherwise, it is NULL.
Windows NT: Requires version 4.0 or later.
Windows: Requires Windows 95 or later.
Windows CE: Unsupported.
Header: Declared in winuser.h.
Buttons Overview, Button Messages, BM_SETIMAGE