Using --eon_force_display=0 on Steams launch options will not only put it on the correct monitor, but also fixes mouse input.

Looks like they are related.

I can confirm this issue on Ubuntu 15.04, but only in fullscreen mode.
But if i use "--eon_force_display=2" to enforce the middle screen (tribblehead setup [ 0 ][ 2 ][ 1 ]) i still cant interact with ui elements

This issue have something incomen witch issue : 0025393: Linux Dual Monitor Problems

In my case after fiddling with monitor cables to sett monitors in default mode 1-2-3 (game runs in main monitor) mouse cursor still offsets way to the right(from gui presumed position) in my opinion its port screen auto detection is the problem. Please repair, it must be easy fix.

Using --eon_force_display=0 on Steams launch options messing up screen resolution (I use two different types of monitors in my set-up 15"+27"+15") what makes offset even bigger.

Linux Mint 17.2 64-bit Cinamon edition, I7-3770k,all 3 monitors ruining from GTX770,Kernel 3.16.0-38, driver: 346.82-0ubuntu0.2

If you have that issue please vote it up !

Same issue here on a 3 monitor setup. Using the --eon_force_display=0|1|2 does not resolve.

Fedora 22 - Build 4.1.6-200.fc22.x86_64 - Nvidia 346.72
i7 3820k - Asus 750 ti - 32GB - 2x S840 Pro Raid 0

--eon_force_display=0 fixes the issue here but it means using the 'wrong' screen.