You can use the GenericPopup() without the input box. The function help for GenericPopup() states that to hide the input string, pass 0 to the responseBuffer.
Here's an example of how to use it. Title will show up on the title bar. Message will show up within the dialog box. If you don't want a message, set the Message parameter to "".
resp = GenericMessagePopup ("Title", "Message", "OK", "Cancel", "", 0, 0, 0,
VAL_GENERIC_POPUP_BTN1,
VAL_GENERIC_POPUP_BTN1,
VAL_GENERIC_POPUP_BTN2);