Known Bugs:
-----------
 - Max. of 100 gadgets.
 - DRAWER_KIND and FILE_KIND gadgets must be at least 10x12 or they'll return
   failure.
 - Trouble will ensue if you try to give an IMAGEBUTTON_KIND gadget an image
   too big to fit in the dimensions you pass it.
 - Some tags (mainly GL_Bottom* and GL_Right*) are untested.

To Do:
------
 - The example programme needs to be a little more extensive.
 - Implement BORDERBUTTON_KIND gadget.
 - Make the imagery for FILE_KIND and DRAWER_KIND scaleable.
 - Capability to recolour imagery for different screen palettes?
 - Scaling for IMAGEBUTTON_KIND gadgets?
 - Event loop handling.
 - More gadget types.