When i change my screen resolution from 1920x1080 to 1280x720, i have noticed, that mouse cursor position in the main menu do not match.
If i'm using Windowed Mode, all works fine.
The only one way to fix it is to using ALT+Tab for switch to another window, and then switch back to ARMA 3. But, after game restart this procedure must be complete again.
This issue i see only in the main menu, in game all works normally, and happened every time i set screen resolution smaller than the native.

Please, sorry for my english, i am from Ukraine.