Widgets can create graphic glitches

I think I didn't expressed it correctly:

If a widget fails to define a valid area no widget will get rendered.

What I meant is:
if a faulty widget fails to define a valid area no widgets at all will be rendered.

You can always add code in appname.boot.js if you want it to run at

Will the code here also run when another app (e.g. the launcher) is loaded?