Graphical Window Sprites
version 1 by Erik Temple
Runtime error "cannot divide by zero" (or similar):
The background has probably not been defined. Be sure you define the background such that it will have been defined before any of the sprite drawing rules fires.
Inform doesn't recognize the "sprite-identity" property, or a table in which it is used:
Inform requires a figure to be defined in the source before it can be referred to. Be sure that your figures are defined in the source *above* the text in which you are attempting to define sprite-identities.
The command prompt is not printing properly:
The system that allows "silent" commands to be issued when the player clicks on a sprite is possibly at fault, since it lightly hacks the printing of the command prompt. If you've customized your command prompt somewhere after the when play begins activity, you may find that you need to also change buffered command-prompt value:
change the buffered command-prompt to "CUSTOM PROMPT>";
Failing this, check the rules in the section on Silent Replacement Commands above to see where things are going wrong.
Be sure that your images are not too large. Images should be sized no larger than you want them to appear onscreen. If performance issues persist, you may want to try preloading sprites (see appropriate section above), and/or using the (hacky) timer-based drawing documented below.