[Bug 32078] Sound Prefernences: No way to stop sound once started

[Lukas Sabota]

Public bug reported:
https://launchpad.net/malone/bugs/32078

Affects: control-center (Ubuntu)
       Severity: Normal
       Priority: (none set)
         Status: Unconfirmed

Description:
If you select a sound and push the play button in the sound preferences
window, it will continue to play until it is finished.  When playing
longer sound effects (log in/log out), this can be a pain.  It would be
a nice polish to change the "Play" button to a "Stop" button (usually a
solid box) once play is pushed.  This stop button would stop the sound
from being played in the middle of the sound.  Once the sound finishes,
or stop is pressed, the "Play" button would return.