The EM_CANPASTE message determines whether a rich edit control can paste a specified clipboard format.
EM_CANPASTE
wParam = (WPARAM) (UINT) uFormat;
lParam = 0;
Parameters
uFormat
Value identifying the clipboard format to try, or zero to try any format currently on the clipboard.
Return Values
Returns a nonzero value if the clipboard format can be pasted or zero otherwise.