Please describe the problem:
This problem is manifesting itself in glabels (http://glabels.sourceforge.net)
which uses libbonoboui to build its menu and toolbars.  The property sidebar
contains a single large composite widget (an object property editor).  When
the height of the window is resized so that the entire widget can no longer
be visible, the widget disappears and replaced with a continuation (arrow)
button (which I don't think should happen if the dockitem only contains one
control).  Now, if you happen to press the continuation button, the dockitem
shrinks, the continuation button also disappears, and no amount of resizing
can restore the dockitem to its previous condition.  I will attach screen-
shots to illustrate.

This dockitem has worked fine up through Gnome 2.6.  The problem seems to have
been introduced with gnome 2.8, but not universally.  I can reproduce it on
Fedora Core 3, but not on Ubuntu Warty.  I also have reports of this
happening on Debian.  The following are bugs filed against glabels related
to this problem.

http://sourceforge.net/tracker/index.php?func=detail&aid=1159774&group_id=46122&atid=445116
http://sourceforge.net/tracker/index.php?func=detail&aid=1064630&group_id=46122&atid=445116
http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=296846

In glabels 2.0.2, I increased the default vertical size of the main window to
avoid the issue, but it is still present if the window is resized as discussed
above.

Steps to reproduce:
1. Obtain and launch glabels 2.0.2 
2. Create a new label (select any media template)
3. Click the Text button
4. Click anywhere in the drawing area to create a text object, this will present
a text object editor in the property sidebar.
5. Resize the window height so that there is no longer room for the object
editor widget/control.
6. Press continuation button (assuming it appeared in step 5)


Actual results:
At step 5, the object editor disappears and is replaced by a continuation/arrow
button.
At step 6, the continuation button disappears, the sidebar/dockitem shrinks in
width, and no amount of resizing can bring the dockitem back to its previous state.

Expected results:
In step 5, I expect the single object to be truncated but rendered in the
dockitem as it did in Gnome 2.6 and still does on Ubuntu Warty.  Since I don't
expect the continuation button, you should never be able to excercise step 6.

Does this happen every time?
It happens every time on every FC3 machine I have tried.  It does not happen on
my Ubuntu Warty machine.

Other information:
I do not believe there is anything in particular that I am doing in glabels to
cause this, since it has historically worked in previous versions of Gnome as
well as on my Ubuntu machine.