This simple addon disables the maximize button on the main map so that you can't accidentally click it when you're trying to close the map.
It was originally a macro that I grabbed from a forum, but I would always forget to run the macro, so -boom- here it is as an addon.
You can activate/de-activate the effects of the addon via slash commands:
/dmm off (turns the addon off)
/dmm on (turns it on)
The setting is account-wide.
Enjoy!