Panner widget?

[harry eaton <haceaton aplcomm jhuapl edu>]

I'm the developer of a fairly extensive application that currently is
based on the Athena widgets.  Presently, it uses a panner/porthole widget,
and I really believe that this is the best thing for this application.

In the documentation, I don't see anything like a panner widget.  Is there
an equivalent widget to the panner widget (sort of like a 2-D scrollbar)
in GTK?  If not, is there one under construction?

I'm considering porting my application to GTK+, mainly because it looks
like it will reduce the amount of effort I have to spend writing
user-interface code.  If there is no panner-like widget, I'd be in the
ironic situation of having to begin by writing a new widget for GTK+!  It
actually doesn't look like it would be difficult to do, but I am concerned
that it would take considerable time before most people would have access
to a "next version" GTK+, that included any new widget I might write.  My
guess is that it will be asking a lot of application users to upgrade
their libraries.  Any advice about how long before the "mess" associated
with updates settles down, and how quickly a new widget (once written and
proven) can find it's way into a released (not CVS) version?

Lastly, my application makes extensive use of various Xt facilites,
particularly in the use of resource files.  gtkrc files seem to provide a
quite limited subset of such capabilites (e.g. accelerator keys, but not
translation overides for mouse button presses, nor abitrary 
application-specific resource types). Any good ideas for doing these sorts
of things?

Thanks,
harry