Last night I upgraded to both Unity 5.1.0f3 and NGUI 3.9.0. Now when I use keyboard input (horizontal and spacebar) while playing in the Editor, my mouse cursor freezes. This does not happen if I use onscreen buttons.
I updated the code to use the new controller stuff rather than the obsolete stuff (sorry I don't remember what it was), but the problem still happens after a few presses of the keyboard input. I can unfreeze the mouse cursor by pressing the "Esc" key, but it freezes up again with a few more presses of other keys.
I am, obviously, not sure this is an NGUI bug, but the changes to controller input listed on the release notes make me suspect NGUI is the problem. I apologize in advance if it is not. No time to troubleshoot further on my end right now.
I'm using a Mac Mini, latest OS.