1	If anything goes wrong, check the popup window/console. It should tell you where the code is
	that caused the error.
2	Error handling is useful to create more stable scripts.
3	Don't call repaint functions such as window.Repaint() in callback function on_size() {},
	especially in pseudo transparent mode.
4	Don't try to assign parameter "gr" from function on_paint(gr) {} with other value, nor try
	to store "gr" in another variable.
5	Consider using Dispose() methods where you can to free up memory. See interfaces.txt for
	where it's supported.
6	Remember to retrieve window width and height in on_size() callback, because their values
	during startup is not reliable.
7	It's NOT recommended to create objects in callback function on_paint(), since it will be
	called frenquently.
