WSPT is an extension procedure to simply write a sprite to the screen under pointer interface, without having to use a full toolkit add-on just to print sprites to a window.
This is a simple wrapper for the QDOS/SMSQ iop.wspt trap. Just load a sprite file into some common heap memory and use this command to write the sprite at a given location in a window channel, e.g.
ad = ALCHP (sprite_length)
Download the WSPT extension from http://www.dilwyn.me.uk/tk/index.html