Using ALT+TAB with hidden Menu Bar shows Menu Bar on key press, not release, of ALT

[ariebesehl]

 * Xed version (3.6.6)
 * Distribution - (LMDE 6)

Issue
Using ALT+TAB with hidden Menu Bar shows Menu Bar immediately on key-press of ALT.

Steps to reproduce

• Set Menu Bar to be hidden in Xed
• ALT+TAB to another Window

Expected behaviour
Xed's Window should remain unchanged if ALT+TAB is issued to system.

Other information
I have replaced line 3472 in xed_window.c with g_signal_connect (GTK_WIDGET (window), "key-release-event", G_CALLBACK (on_key_released), window); and renamed the function (line 119) on_key_pressed to on_key_released for consistency.

I have installed these changes as a local .deb on my system and it seems to have achieved the desired effect, but I am unsure if I may have caused another collateral issue herewith, and am testing the current changes on my system in Xed's daily #driving to ensure functionality remains unchanged.

If the changes above are deemed acceptable, I'd gladly do a PR for it.