Resize panel when contained Tree expands? (newbie)

[BDR-Gary]

I'm a complete GWT newbie...

My page is a set of panels in a VerticalPanel. One of those panels is
a HorizontalPanel with a Tree on the left and a panel of widgets on
the right. When I expand a tree branch, I would like the containing
HorizontalPanel to expand so that the newly exposed leaf nodes are
visible. This would, of course, cause the other panels below this one
to move down the page.

I find that when I click the little icon with the + sign next to the
branch element's name, it changes to a - sign, but the supposedly
exposed leaf nodes are not visible because the containing panel did
not resize. If I then click on the text of the branch element's name,
the containing panel does resize.

If I then close that branch, the panel does not resize. If I click on
the branch name, it does not resize. If I click on a different node
above the branch, the panel then does resize.

Is there a way to get the containing panel to resize appropriately
when expanding and collapsing a branch element.

I'm running the GWT 1.7 Eclipse Galileo plug-in on Ubuntu 9.10, and
testing with the hosted browser. Thanks.

[BDR-Gary]

SOLVED: The problem only occurs in the hosted browser. The tree works
as expected in other browsers.