Follow this link to the latest revision. The details below mostly apply to that too.

This is an idea I've been thinking through about making volume adjustments to applications quicker, particularly when they don't have their own control (e.g. Firefox) or aren't immediately accessible (i.e. minimised, behind another window, or on another workspace). It started before the announcement of windicators, which are certainly an interesting way of achieving that goal. But, since not all applications will use windicators straight away, there will always be users who "just want to look in one place", and, as I've just mentioned, windows aren't always at hand, I think this idea still has potential, so I'm opening it up to public feedback here.

In addition to the current master volume slider and link to the Sound Preferences, there are volume sliders for up to three^[1] open sound-emitting programs,^[2] displayed in the order that their windows were last in focus.^[3] This provides a more discoverable way of altering the volumes of individual applications than the Applications tab of Sound Preferences, while being more centralised and available than windicators, offering a quick, at-a-glance comparison.

In contrast to current behaviour, when a channel is muted, its slider turns grey; muting the master volume greys out all sliders. Each volume slider is movable even when muted, as with a real mixer.^{[4, 5]}

The final item, "Applications Mixer…", allows for adjustments to more applications by opening a dedicated mixer window.^[6]

The mockup doesn't mimic all methods of moving the volume sliders. Clicking on the 0 and 100% icons at each end, or on the slider either side of the handle is demonstrated; however, dragging directly, scrolling while hovering, and using the arrow keys (up/right +, down/left -) are not, although they would be viable options in the real menu.

Thoughts, opinions, or other kinds of feedback? Add a comment to the blog.

[1] With more than three, the menu becomes unwieldy, and a dedicated mixer becomes more appropriate. If no sound-emitting applications are running, the menu becomes almost identical to the current applet.

[2] Firefox should appear as "Firefox", not "ALSA plugin [firefox-bin]", as in the Sound Preferences' Applications tab. It's a predictable string that should be easily replaced.

[3] The Alt-Tab switcher can determine this order, so I'm sure the volume menu can too. This limits the distance needed to move the cursor.

[4] This allows the reaction of quickly mute, turn down, then unmute to unexpectedly loud noises.

[5] Possible confusion—of the "I move the slider but there's still no noise" kind—caused by this behaviour should be mitigated by the grey colour and the "Unmute" in the nearby title(s) explaining the actions necessary to hear sound beyond simply turning it up.

[6] Ideally, this would be a purpose-built interface that included simple metering, an indication of how master volume level limited individual volume maxima, and an orientation option. In its absence, opening the Applications tab of the Sound Preferences is a functional, though more basic, compromise option.