BUG still in 4.1: hide/show the tree widget

[Falk Brettschneider]

Hi,

If you do these steps, the toolbar will get in a wrong state:
- if the treeview is visible, click on the toolbar button to hide it
- then move the mouse cursor to the main widget border on the left-hand
side
- drag the tree widget border on the left-hand side to the right
  (now the tree widget is getting visible)

After these steps the treeview is visible but the toolbar button is not
in state "ON" :-(
-- 

Ciao,
--Falk