This is probably an "idea" but i'll be honest i don't know where in the ideas to put it so i'm going to drop it here.
Some how bentley missed creating a close file icon back before they fixed the "file" area in CE and it was dog slow i customized the quick launch bar to bypass it's existence by just putting most of the file navigation buttons there. There has never been an icon for close file it defaults to the "wrench" and it's always bugged me. I was getting ready to make my own icon and just customize that button and figured maybe this bugs others and bentley wants to slip it into an update as i'm sure it wouldn't take much to fix this on their end.
If not in a year i'll probably just go about making my own anyway...
-Grant
I've just created one. I used this icon from the stock Bentley ones. The keyin is 'Close Design'
See i'm almost there but at the same time i feel like this is one of those silly over sites that Bentley should just fix as a good steward of their software... Honestly i think nobody at Bentley noticed and just needs it pointed out. But i was about to do the same thing you did when i decided to bring it to their attention we'll see what happens.
Interestingly V8i doesn't have a close icon either.