[unity 5.6] Using Alt+F1 or Alt+F2 sends a ";3P" or ";3Q" to the active windows

@Daniel: this doesn't seem to be a compiz issue, I can't reproduce it with unity 5.4 (in precise) + latest compiz in the ppa alone

Setting as high as we don't want to release a regression.

This appears to be a Unity bug. Gnome terminal is correctly receiving the Alt+F2 keystroke because Unity has told compiz that it has not consumed the keystroke (returning false):

bool UnityScreen::executeCommand(CompAction* action,
                                 CompAction::State state,
                                 CompOption::Vector& options)
{
  SendExecuteCommand();
  return false;
}

So the terminal will receive the Alt+F2 escape code which is ^[O1;3Q
Gnome terminal at least, does not understand such Alt escape codes in the terminal. So it consumes the standard part of the input up to the semicolon (^[O1), and outputs the rest (;3Q) as regular text.

This bug should be fixed simply by changing UnityScreen::executeCommand to return true. That tells compiz that the key combination should not be passed to the app.

The fact that this bug was never visible before seems to have been a bug in compiz-core, which is obviously now fixed.

For some reason I can't reproduce this bug. And I can't upgrade my precise machine to test the latest packages. But I think you will find this patch is the fix.

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I notice this happens in oneiric too (unity 4 / compiz 0.9.6). Pressing unused key combinations like Alt+F3 or Alt+F12 outputs part of the control code to the gnome-terminal window.

See also similar bug 944521.

OK, I have found the two causes of this bug. Half in Unity half in compiz.

1. As per comment #3, Unity key callbacks return false, which means compiz should pass the keys on to apps. They should be returning true.

2. Compiz incorrectly passes the keys though to apps even if a plugin has handled it and returned true. But only if a plugin is bound to <modifier> and the user presses <modifier>+<other-key>. Like Unity is bound to <Alt> and you press <Alt+F2>

Sorry I made a mistake in setting up my test environment. There is nothing that needs fixing in compiz-core. I can confirm that simply changing the Initiate callbacks in unityshell.cpp to return true will prevent the Alt+Fn key codes from reaching the active window.

I was right in comment #3.

Sam's branch looks right. Could someone please assign this bug to smspillaz? LP won't let me.

This bug was fixed in the package unity - 5.6.0-0ubuntu1

---------------
unity (5.6.0-0ubuntu1) precise; urgency=low

  * New upstream release.
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      (LP: #862972)
    - compiz crashed with SIGABRT in __gnu_cxx::__verbose_terminate_handler()
      (LP: #926793)
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      between Lenses and 'TAB' by itself moves the focus between categories
      (LP: #891648)
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    - unity-applications-daemon crashed with SIGSEGV in
      dee_sequence_model_free_row() (LP: #916356)
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      when dragging a window (LP: #928805)
    - lenses are loaded on start, should be lazy loaded (LP: #929506)
    - Trash icon jumps about when trying to drag an icon onto it (LP: #932365)
    - HUD loses keypresses for the first second after opening (LP: #932906)
    - HUD doesn't give the focus back to the active application after dash/hud
      use (LP: #934061)
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      -GNOME-Keywords or X-AppInstall-Keywords) (LP: #941231)
    - Support FD.o Desktop Actions spec (LP: #942042)
    - Unity hangs when touching my touchpad/trackpad (LP: #942625)
    - [regression] Pressing alt doesn't show the menu title bar in top panel
      (LP: #943194)
    - Alt + F (or other mnemonic) doesn't work in gnome-terminal (LP: #943239)
    - [unity 5.6] Using Alt+F1 or Alt+F2 sends a ";3P" or ";3Q" to the active
      windows (LP: #943456)
    - [unity 5.6] holding alt and pressing a direction opens the alt-tab list
      in a buggy way (LP: #943902)
    - [unity-5.6] can't enter accents (^o->) in the dash since recent updates
      (LP: #944674)
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      highlights another, so there are 2 highlighted icons (LP: #817436)
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    - Keyboard shortcut - F10 shortcut is used to show menu and this is wrong
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      available for purchase (LP: #916121)
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