Description of problem:
It would be nice if an user had the possibility to collapse folders in the simulation results which would make the view port a bit smaller in size and he would not have to scroll from top to bottom (and vice versa). Currently the folders in the simulation results cannot be collapsed.

Version-Release number of selected component (if applicable):
6.1.0 ER6

Steps to Reproduce:
1. create a simple process (Start -> Manual Task -> End)
2. run simulation
3. go to the simulation Results tab
4. collapse any folder (Process, Process Elements, Paths)

Actual results:
The IE console shows this error:
"Unable to get property 'ui' of undefined or null reference"
whenever I try to close an expanded tree item.

Based on BZ1049506, this is a problem in Ext library (v2.0.2). Newer versions of this library are not an open source.

Expected results:
An user can collapse folders in the simulation results tree.

Additional info:
Maybe the own implementation of this tree may help.