just tested with firefox. what firefox does is that when you press the alt key it closes the menu hence releasing the grab. In unity alt is used for different purposes.
** Changed in: unity (Ubuntu) Status: New => Won't Fix -- You received this bug notification because you are a member of Desktop Packages, which is subscribed to unity in Ubuntu. Matching subscriptions: dp-unity https://bugs.launchpad.net/bugs/1005312 Title: Shortcuts - shortcuts don't work when application indicators are visible Status in “unity” package in Ubuntu: Won't Fix Bug description: Shortcuts will not work with: - open application indicators (e.g. switch user account, time and date settings, etc) - opened sound level bar in movie player and similar stuff from other apps. - opened dash home - etc. This bug blocks an efficient work proces for the user and the usage of shortcuts is no longer predictable. Also the chance it occurs is pretty high. * Steps to reproduce Open a windowed app (e.g. firefox) Show desktop using the shortcut ctrl-alt-d Maximize the windowed app again (e.g. firefox) Left click on 'time and date' in the upper right corner (leave the application indicator opened) Show desktop using the shortcut ctrl-alt-d * Expected behavior The windows app is minimized. * Current behavior Nothing happens (the windowed app is not minimized) To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/unity/+bug/1005312/+subscriptions -- Mailing list: https://launchpad.net/~desktop-packages Post to : desktop-packages@lists.launchpad.net Unsubscribe : https://launchpad.net/~desktop-packages More help : https://help.launchpad.net/ListHelp