my mouse Can't reach all the optiions on the menu if its not on windows borderless... it only works on windows borderless, not on fullscreen or just plain windows. in fact, it wont even work on borderless, until i switch the screen type.... playing on borderless with mouse is annoying because when looking down and shooting, using the mouse button to shoot causes me to click on the hidden taskbar... which has gotten me killed a few times. I play with a ps3 cpntroller just bcause of the issue.... i wanted to get use to pc cpntrols with a mouse and keyboard for far cry 3, since i am new to pc gaming and built my first pc about a month ago, but iI just can't use a mouse if i can't see all of my map because my mouse won't move any further, or can't reach certain options in the menu, or constantly click on the hidden task bar, because all i can play on is bordeless... i had this issue since the game came out. i do not know if anyone else is experiencing this or not... the mouse works fine on primal carnage, so i'm pretty sure its not my mouse or computer.
if u have a desktop shortcut for uplay, right click it, click on properties, the compatibility, select "disable desktop composition", click apply, and ok. if u have the game on steam u will probably have to go to program files86>steam>steamapps>common>far cry 3>bin>farcry3. Right click on farcry3 application file and do the same thing as i said above.
allthough this did work, it created huge screen tears in the game while looking up and down... thought it was my graphcs card, but i never had the issue before in far cry3 until i did what you told me. i then put it back to how it peviously was, and the creen tears are no longer there... but i can't use the mouse, as before...frustrating.
after you change this it may have changed ur resolution in game so check that in the games settings. if u have vsync on there shouldn't be any screen tearing. also make sure the settings in game are set to fullscreen. even if its obviously in fullscreen on ur screen the game settings may not reflect that. i had this issue on day 1.