A window can process the WM_DESTROYCLIPBOARD message in order to free any resources that it set aside to support delayed rendering. For example the Label application, when copying a label to the clipboard, allocates a local memory object. It then frees this object in response to the WM_DESTROYCLIPBOARD message, as follows.
case WM_DESTROYCLIPBOARD:
if (pboxLocalClip != NULL)
{
LocalFree(pboxLocalClip);
pboxLocalClip = NULL;
}
break;