Comment 20 for bug 919437

This has just started happening with me on Ubuntu 14.04, after I updated my HWE stack. My laptop has an HDMI attached screen above it, so I use 1-vertical screens, 2 wide, which gives me a 2x2 set up.

When my screen locks, random windows will move themselves to a non-existent vertical screen below my laptop's screen.

To get them back, I start CCSM, choose General Options, then choose Desktop Size and change my vertical desktop size to 2, drag the windows back to a visible workspace, then change my vertical size back to 1. I can also use the methods described in this bug report.

If I leave my vertical size at 2, the windows still jump down randomly and I then have to add a third layer to my vertical desktop size to get them back, so the desktop size itself appears to be irrelevant.