Quick Entry Short Cut - Option Key
 

I want to set the quick entry shortcut for Omnifocus to Option+Space . When I try to do so in the General Preference>General panel, it just gives me an error beep. In fact it gives me an error beep for Option+AnyOtherCharacter .

I can set the quick entry short cut just fine to Ctrl+AnyOtherCharacter or Option+Ctrl+AnyOtherCharacter, but for some reason it doesn't like Option being the sole modifier.

Any ideas?

Option + <other key> in OS X is used by the text input system. It means "type an alternate character". For example, option-8 gets you a bullet point like this: •

and here's "option-q,w,e,r,t,y": œ, ∑, ´, ®, †, ¥

Since those combinations are used as part of the text system, OmniFocus can't use them for the quick entry shortcut. It only gets a chance to handle the keyboard event if the app you're running declines to do so.