Browser layering

[hh]

> Brian M. wrote:
> May be able to take a screen shot, show it, hide the real browser,
> show the tree widget. That does require that the browser contains
> something static and user can’t interact with the browser while the
> tree is visible.

This is probably the easiest solution. But problems may also arise
because we can't take a "snapshot from widget browser" but only from
its (global) rectangle.