a few stray bug fixes and issues found with jslint. It suggests a larger, incremental refactoring to make the code more maintainable.

still two regexes that don't comply

fix ambiguous function name, and rename variable to clarify difference between DOM window and nw Window

* add a canvas_mouseup call when clicking an empty part of the canvas after editing box text

put iemgui and canvas dialogs near the place where the popup menu appeared, and center the other dialogs