How to remove an app from the taskbar?

[David O'Shaughnessy]

Hello all, is there any way in XFce4 to have an application not appear
on the taskbar? So it is running yes, but not showing up on the taskbar.
I asked the creator of the application if he could code this feature in
and he told me;

"The required functionaility should be part of your window manager. You
should be able specify that windows with certain properties (i.e. the
WM_CLASS for XMMS) are hidden.

Under GNOME2 it is provided by the devilspie utility which uses the
freedestop.org WM spec to make these things happen. If your window
manager doesn't provide the functionailty natively, but does support the
freedesktop.org WM spec then you may be able to use that."


I'm not sure what this devilspie utility is, but maybe this could help?
Thanks.