I set the ‘undo tool’ hotkey to some value … it works for one button press then refuses to work again. :td:
I’ve assigned hot keys to various brushes… no problem.
But ‘undo’ just does not work, even though the tooltip shows that a key has been assigned!!
This is a major pain … anyone else had this problem?
If you look in your ZStartup\Hotkeys folder you’ll find a file named 'StartupHotkeys.TXT. Open the file in a text editor and alter the line that reads:
[EDIT:TOOL:UNDO 1,1146] // Alt+Z
to:
[EDIT:TOOL:UNDO,1146] // Alt+Z
(Obviously the hotkey number will be different for you.)
That seems to have worked
I changed
[EDIT:TOOL:UNDO 1,46] // Alt+Zto
[EDIT:TOOL:UNDO,1146] // Alt+Z
what do the numbers mean?
The number between the last comma and the square bracket is the hotkey code. The ‘1’ that you removed is the Undo number. By removing that you ensure the hotkey works for any of the Tool:Undos - left in, the hotkey only works for ‘Undo 1’, which was the problem you were having.
Thank you so much this was seriously begining to piss me off. 
I thought it had to do something my customInterface that i had created, cause i needed to remove it from the start up folder and than manually load it so that undo would work, other wise it wouldn’t work.
your solution seem to fix the problem. Cheers!
edit: nevermind :o
I can’t believe it is the year 2012. and this problem still exists in the latest version. and this fix doesn’t work anymore. I just can’t believe it. I’m going to have to make a video avgn style to explain how broken zbrush is. I’m at my wits end with this crap, that I need to explain every single way this is broken and it’s not even funny anymore. I can’t get real work done with this thing without having to do research and swim through forums of fixes that are no longer applicable to the current version. or pixologic wiki’s with outdated information. So sick of this crap.