Are there pre-made stock icons for that?

From gnome-icon-theme you have you could use the following replacements
play.png => stock_volume.png
noplay.png => stock_volume-mute.png
record.png => stock_mic.png
norecord.png => OK that one is still not there, but should not be too difficult
to make. If you think stock icons are a good idea, we could file a request for
such an icon

I'd like that, yes. I'll make this bug depend on it and use it when done. Thanks.

Jaap, did you file a bug about that?

(In reply to comment #4)
> Jaap, did you file a bug about that?
> 

I just did.

Could you make this depend on that?

This bug already depends on bug 469319. I thought bugzilla sent out a notification for that.

2008-03-24  Jaap Haitsma  <jaap@haitsma.org>

        reviewed by: Marc-Andre Lureau

        * configure.in:
        * gst-mixer/Makefile.am:
        * gst-mixer/gnome-volume-control-ui.xml:
        * gst-mixer/icons/16x16/Makefile.am:
        * gst-mixer/icons/16x16/devices/Makefile.am:
        * gst-mixer/icons/16x16/status/Makefile.am:
        * gst-mixer/icons/Makefile.am:
        * gst-mixer/pixmaps/Makefile.am:
        * gst-mixer/src/Makefile.am:
        * gst-mixer/src/button.c: (gnome_volume_control_button_class_init),
        (gnome_volume_control_button_init),
        (gnome_volume_control_button_dispose),
        (gnome_volume_control_button_new),
        (gnome_volume_control_button_clicked),
        (gnome_volume_control_button_mouseover),
        (gnome_volume_control_button_mouseout):
        * gst-mixer/src/button.h:
        * gst-mixer/src/element.c:
        (gnome_volume_control_element_class_init),
        (gnome_volume_control_element_init),
        (gnome_volume_control_element_new),
        (gnome_volume_control_element_dispose),
        (gnome_volume_control_element_change):
        * gst-mixer/src/element.h:
        * gst-mixer/src/main.c: (main):
        * gst-mixer/src/misc.c:
        * gst-mixer/src/preferences.c:
        * gst-mixer/src/stock.h:
        * gst-mixer/src/track.c: (gnome_volume_control_track_add_title),
        (gnome_volume_control_track_put_switch),
        (gnome_volume_control_track_add_playback),
        (gnome_volume_control_track_add_recording),
        (gnome_volume_control_track_add_switch),
        (gnome_volume_control_track_add_option):
        * gst-mixer/src/track.h:
        * gst-mixer/src/volume.c: (gnome_volume_control_volume_class_init),
        (gnome_volume_control_volume_init), (cb_mouseover), (cb_mouseout),
        (get_button), (gnome_volume_control_volume_new),
        (gnome_volume_control_volume_dispose),
        (gnome_volume_control_volume_size_alloc),
        (gnome_volume_control_volume_expose):
        * gst-mixer/src/volume.h:
        * gst-mixer/src/window.c: (menu_item_select_cb),
        (menu_item_deselect_cb), (connect_proxy_cb), (disconnect_proxy_cb),
        (cb_change), (cb_exit), (cb_preferences_destroy), (cb_preferences),
        (open_uri), (cb_help), (cb_about),
        (gnome_volume_control_window_dispose),
        (gnome_volume_control_window_class_init),
        (gnome_volume_control_window_init),
        (gnome_volume_control_window_new):
        * gst-mixer/src/window.h:
        Use GtkUIManager i.s.o. deprecated libgnomeui
        Remove libgnomeui as a dependency
        Use tango icons if possible and make all icons themeable
        Install deprecated icons from the application itself. Now we just need
        a pixel pusher to make us some nice tango icons for the remaining icons
        Use G_DEFINE_TYPE macro for our own types
        Fixes bug #494031 and bug #310883