When I tab out of the game (for example to switch to other music on my media player) and then switch back to the game the mouse doesn't work as it is supposed to anymore.

More detailed description: Usually one selects stuff with the pointy end of the cursor (see before.jpg). But after switching back to the game the behavior has changed (see after.jpg). Then the cursor selects the things that are a couple of pixels below the pointy end of the cursor (see after2.jpg). One way to fix this (once the problem occurs) is to switch to "window mode" in the game menu and then back to "full screen mode". After doing so the mouse works as it should again.

Unfortunately this behavior is very annoying, as I tab out of the game quite often. Furthermore I am pretty sure that the release version was not afflicted by this and that one of the updates introduced this bug. (Since I tab out of the game quite often and was so glad that tabbing out of the game worked -- and worked so well -- with the release version.)

System information:
GNU/Linux Mint 17
Intel(R) Xeon(R) CPU E3-1240 V2 @ 3.40GHz
AMD/ATI Radeon 6870 (latest free drivers via the ~oibaf PPA)
32GB RAM

Need more information? Should I try something specific? Just tell me... ;>

The problem persists and the last update (that came with DLC2) did not fix this bug. (I tested it a couple of minutes ago with my other copy of Valhalla Hills, that I bought on Steam, where the update and DLC2 is already available.)