XClientMessageEventUnfortunately, X client messages (of type XClientMessageEvent) are limited in size: you can only transfer up to 20 bytes within them. For this reason, M*TIF applications use a ``drag window'' with special properties attached to it to transfer any additional information which uses up to much space. Some of the protocol messages therefore just refer to a data structure stored with the drag window.
_MOTIF_DRAG_AND_DROP_MESSAGEThe various X client messages used for the drag or drop protocol share
a common header and some common settings.