I just whined about this elsewhere, but this makes a good post, so:
1. a very good feature of default Win32 message boxes is that they implement Ctrl-C to copy the error message and window title into the clipboard (formatted and everything)
2. way too few people know this, and accordingly, custom message boxes basically never implement this
3. if you work on custom UI libraries that have some message box facility, you should!

@rygorous people doing custom controls/UIs get even way more basic things wrong. Your modal message box, does it accept Esc/Enter keys? How about space? Tab?

A drop-down list, can I start typing and it scrolls to these entries? PageUp/Down? Arrow keys?

*Soo* much custom UI shit is made to only work with mouse and touch. Ugh.

@aras Yes.