I wanted to mention this as I noticed it was already reported as fixed in release notes for OmniGraffle 5.2.1:
I have assigned Cmd-' to Show/Hide Guides, and every time I use it, I get
Is this the same bug?
|Fixed a bug where a custom keyboard shortcut for showing/hiding Guides would result in an error.|
-[NSMenu submenuAction:]: unrecognized selector sent to instance 0x920fa0