Pressing Ctrl+Alt causes focused window to disappear if it wasn't maximized

[Dan]

To be honest I'm not sure how to provide extra details about this issue, but it really is frustrating as sometimes it causes loss of unsaved data. I'm willing to provide any required data, and debug the the issue in any way I can if it helps.

The issue is always reproducible for me. Any window that is not maximized, when in focus, disappears after pressing Ctrl+Alt.

It behaves as if it was moved to another "non-existing" workspace, so the application would still be shown as open in the Unity Launcher. That is, an empty arrow is shown next to the icon instead of a filled one. I tried disabling workspaces with unity tweak tool since the shortcuts unusable in state (They all contain Ctrl+Alt in them).

If the application that disappeared had only that one window opened, it is possible to recover the lost window by clicking on its icon in the launcher. But it doesn't work if you try to select from the list that shows when pressing Alt+Tab (I think it's called the App switcher?)

The biggest problem, is when having multiple windows of the same application opened. This makes it impossible to recover the lost window unless all the other ones were closed first. (So I'd be able to open it by clicking on its icon in the Launcher). Which is problematic as sometimes i accidently use a shortcut that contains a Ctrl+Alt while I have terminal windows running script or ssh etc. (The default shortcut to open a terminal window is Ctrl+Alt+T which makes this even worse)

Steps to reproduce:
- Open a terminal window
- Open another terminal window
- Have any of the two terminal windows in focus
- Keep that window non-maximized
- Press Ctrl+Alt
- Window disappears

Notes:
- Ctrl+` cannot recover the window (Although the application switcher still sees that there are 2 open windows of that app (It shows the 2 squares)
- Clicking on the terminal icon in the launcher only opens the second (and still visible) terminal window
- Right clicking on the launcher icon does not list the hidden window.
- In some cases the application disappears completely from the App launcher as well.

lsb_release -rd
Description: Ubuntu 16.04.1 LTS
Release: 16.04

apt-cache policy unity
unity:
  Installed: 7.4.0+16.04.20160906-0ubuntu1
  Candidate: 7.4.0+16.04.20160906-0ubuntu1