The tree view filter 
serves for searching and finding objects within the tree view of a workspace, workdesk, nailboard, or cable drawing.
Example:In the Filter in Tree view field enter "pe" and press ENTER or the click the button Filter Tree view for the given keyword. The tree view shows all the objects with "pe" in their name or REFDES, such as "VolumenkörPEr" or "M1-PE". All categories with results will be displayed in tree view, others will be hidden as they do not contain results with "pe".
If you want to cancel the command, click the cross 
.
Note:
The Search field in the upper right-hand corner of the application serves to easily find and select items containing the entered string within their part number or properties.
You can also use Panel Global search to find objects within a workspace, workdesk, nailboard, or cable drawing.