System: Linux Mint 17.3 (based on Ubuntu 14.04 LTS), 4-core i5 3.33 GHz, 12GB RAM, ATI HD 5770 w/ 1GB RAM, 2 x 1280x1024 monitors: monitor 1 at the left and monitor 2 at the right.
Steps to reproduce issue:
1) Enter full-screen mode (or start-up in full-screen mode): a full-screen window is created on monitor 1, mouse capture works fine and the view direction can be rotated at will.
2) Alt-Tab to another application.
3) Alt-Tab back to Rising World: the full-screen mode is correctly restored in the monitor 1 and everything works, except that mouse capture is lost. I.e.: by moving the mouse to the right (toward monitor 2), eventually it exits from monitor 1 into monitor 2: a standard mouse cursor appears in monitor 2 and view direction cannot be controlled any longer. To maintain standard behaviour, one has to bring the mouse pointer back into monitor 1 and be careful never to leave it.
Windowed mode works fine.
This issue is not really severe and it only shows up in full-screen+multi-monitor setups, I assume; however it is annoying and breaks the game playing flow. If more info is needed, I can probably provide it.
As this is the only bug I encountered in ca. 40 hours of playing RW, I think it to be surprisingly stable for an Alpha! Kudos to the developers 
!
