I customize the software to fit my quirks. The Firefox user interface, for example,
is all laid out CSS and in an HTML like language called XUL. So if you can make
and edit a web page, you can edit your browser.

I do the same thing switching between IE and FF. Always trying to close the browser rather than the tab.
So go into the CSS and make that close button hot pink or something that will
grab your attention and make you think for a split second before clicking it.
Once you start playing with it you'll find other things you'd like to change.
For example, I added a CSS rule to display all banners at 1/4th their normal size.

Of course I have this flexibility because I use no Microsoft software. Virtually
everything I use is open source, so I have full source to make any changes, but
normally I don't need the source - just configuration. The non-MS software I use
is built based on the idea that the user should be in charge of the machine, not
the other way around. I feel for those of you using MS style software that
assumes the user is too stupid or lazy to figure out what they want to do, and
therefore the machine should be in charge of the person.