black volume control icon (on a black background)

[grok]

I have the slight problem of volume control icon being totally black, which does not work well on a black background. it's still fully working (and can open pulseaudio volumes by right-click and selecting "volume settings", but only when I remember it can do that)



any idea what icon file is used?
it's hardly visible at all even when the taskbar is set to use "background.png" for appearance (as for "system theme", beside not liking the light grey I get, it's the clock that gets impossible to read along with the "NA" displayed by temperature monitor).

this is on linux mint 13 mate, with lxde apt-got afterwards.
btw the white outlines on resource monitor applet disappeared after an applet (the apparently redundant WNCKP) did reset lxpanel so it looks slightly better now.

at least I'm glad there are a new applets.