Alt-F10 locks up Unity

I don't have this issue with the same Unity version from the same PPA.

Which graphic card/driver do you have? That might explain part of the issue.

I have experienced the same problem. I can reproduce it all the time in the following way:

1. Focus any application
2. Press and hold alt
3. Tap F10 a few times
4. Release alt

After this, unity is broken and unusable - the only way to get it back is restarting compiz. It seems rather critical. Currently I'm using unity 5.4.0+bzr2064ubuntu0+654 with compiz 1:0.9.7.0+bzr3035-0ubuntu1~ppa3. My system is an i386 with the fglrx graphics driver.

+1 on both i386 and amd64 machines using unity-team/ppa today.

3v1n0, your fix for this bug is missing the safety check to avoid crashing on Alt+Enter. Like we did for:
https://code.launchpad.net/~vanvugt/unity/fix-960957/+merge/98593

I wonder if that's going to be a problem?...

This bug was fixed in the package unity - 5.8.0-0ubuntu1

---------------
unity (5.8.0-0ubuntu1) precise-proposed; urgency=low

  * New upstream release.
    - New "push mouse offscreen" feature really difficult to get (LP: #923749)
    - unity-2d-panel crashed with SIGSEGV in
      unity::indicator::DBusIndicators::Impl::RequestSyncAll() (LP: #864737)
    - Pressing "Alt+Enter" causes compiz to crash in CompOption::value() from
      unity::UnityScreen::showLauncherKeyTerminate (LP: #960957)
    - SEGSIGV after unplugging external monitor (LP: #962693)
    - Background colorization should use a different heuristic (LP: #865239)
    - compiz+unity3d generates > 50 wakeups a second on idle system
      (LP: #917210)
    - [FFe, UIFe] HUD - The HUD does not respect launcher autohide or icon
      size settings (LP: #921506)
    - clicking on folders in the file lens does not open nautilus
      (LP: #921665)
    - No text inside multirange filters (LP: #927710)
    - can't alt-tab restore minimized uis which have an instance on another
      workspace (LP: #933397)
    - Ubuntu Software Center Unity launcher integration is not working
      (LP: #932280)
    - The line separator between the launcher and the dash is cleared when
      selecting a category (LP: #941082)
    - unity-panel-service crashed with SIGSEGV in g_hash_table_foreach()
      (LP: #937119)
    - Alt-F10 locks up Unity (LP: #948522)
    - multimonitor, launcher: Provide an option to display either a single
      launcher or a launcher on each display in a multi-monitor environment
      (LP: #950136)
    - multimonitor: Please give me a way to turn off sticky monitor edges
      (LP: #946104)
    - Unity 5.6: key bindings (such as Super) don't work on empty workspace or
      on slow/loaded systems (LP: #953089)
    - Alt+arrows keyboard shortcuts don't invoke Back and Forward navigation
      (LP: #953783)
    - HUD is sending 2 menu signals instead of 1 (LP: #956878)
    - 6th item of HUD not fully visible (LP: #957229)
    - HUD: seems to trigger operations more than once (LP: #960503)
    - Launcher gets always desaturated when using HUD on secondary monitor
      (LP: #961169)
    - [5.8 pre staging] launcher is displayed on the left screen, not the
      primary one (LP: #961281)
    - launcher icons do not re-saturate after dash is closed (LP: #961844)
    - Launcher shows arrows for applications on all workspaces (LP: #961977)
    - Dash - Implement overlay scrollbars in Dash (LP: #608124)
    - [UIFe] Dash - No message displayed when no results are returned in the
      Dash (LP: #711199)
    - Dash - "See more..." line should be base-aligned with section header
      (LP: #748101)
    - Dash - Missing category separator line in dash (LP: #850984)
    - Dash and Launcher - As soon as a user starts dragging a file from the
      Dash, there is a 'flicker' before the Launcher icons that are valid drop
      receptacles re-saturate (LP: #863230)
    - Dash - When multiple results have equal string match relevancy ranking,
      those with equal ranking should be then sorted by frequency of use.
      (LP: #871900)
    - Keyboard shortcut - F10 shortcut is used to show m...

I don't see this fixed for current Unity

$ unity --version
unity 5.12.0

Yuriy, if you still have problems in Unity 5.12, please log a new bug.