Clear all input traps if we ran out of clients
Dont update dynamically
Reset shell focus when all apps exit
* Clear all input traps upon death of the last client
* Reset shell focus if all apps exit. Fixes: https://bugs.launchpad.net/bugs/1203698, https://bugs.launchpad.net/bugs/1204299.

Approved by Ricardo Salveti, Michał Sawicz, PS Jenkins bot.