In 3.1.0, (in both Linux and Windows), many of the keyboard shortcut keys in the forms don't work properly as they clash with the main menu.
For example, in the New Item form:
Alt+I should move you to the "Inventory UOM" field, but instead opens the main Inventory menu
Alt+S should save the item, but instead opens the Sales menu
Alt+C should work as cancel, but instead opens the CRM menu
I use the keyboard a lot, and it's a far quicker way to work if you have a lot of things to enter, glitches like this really slow me down.
I'm not sure how to fix this though with the amount of menus you have.
Might it be possible to use a standard set of shortcuts in the forms for things like Save & Cancel? Ctrl+S or Esc?
And then after that, I think you just need to look at the keys used in forms more carefully. It's no good having them at all if some work and some don't.