"floating panel" window type

[Havoc Pennington <hp redhat com>]

Hi,

I have a constant stream of requests in Metacity bugzilla to have XMMS
and gkrellm behave differently from others windows. So, need to sort
out how these apps work within the EWMH framework
(http://www.freedesktop.org/standards/wm-spec/). Otherwise there's no
way to have WMs handle them correctly without the user manually
configuring a bunch of stuff.

Basically the desired behavior is: 

 - stays on top of normal windows, but below its own dialogs 
   and below FULLSCREEN windows and potentially below panels
 - skips normal task list, but in Ctrl+Alt+Tab for panels
 - sticky
 - decorated or not according to Mwm decoration hint.

Probably the same behavior desired for "floating panels" in GNOME.
Essentially small stuck-to-glass applications.

(Of course XMMS and gkrellm could have config options to optionally
present themselves as normal apps as well.)

Assuming panels are always on top, a change I'm planning, XMMS and
gkrellm could probably just set their type to DOCK and go with that,
just like a panel. The one problem there is that DOCK windows are
never decorated.

If we want WMs to have the freedom to implement a raise-on-mouseover
type of policy for panels (as Metacity currently does), or want to
have floating-control type windows that are decorated, we would need
to add a FLOATING type or something to the WM spec to distinguish XMMS
and gkrellm from other panels.

What do people think?

Havoc