show as tree: this setting allow swap between a tree view and a table view of the cases.
It is possible to swap this setting also from the checkbox of the lower status bar.
The tree view shows the cases classified as a tree based on its 'tags', a ordered sequence of words (these tags are inherit from the name of the XML file with cases definition)
The table view shows the cases as a flat table, ignoring the tags.
The table view allows for example order the cases by the header of a column, e.g. to show them alphabetically or to show them ordered by failed or not.
The information is more condensate in this kind of visualization.
The tree view allows to expand only the selected branch, and to run some selection of cases based on this classification. 
Note: Pressing a key the next test case starting with this letter will be selected.
Note: It is possible use <ctrl>-c to copy the selected rows to the clipboard (e.g. to be pasted in a Excel table)