To be honest, Esc key is not natural for a lot of users.

The best way should be right-click on the ruler and a menu with :
- options
- exit

and not directly configuration !

Edit : replace config with options

I just implemented it! I will update in the next release, which will have a much smaller footprint.

I've a suggestion

In options add a checkbox to specify "always on top" and perhaps a "systray mode" too, don't you ?