Selecting And Deselecting rows in the TreeView

["SaiKamesh Rathinasabapathy" <rsaikamesh gmail com>]

Hi,

I added Treeview in a Window. At the left side of the TreeView I added a button named as "Add Patients". 

If a row in the TreeView is selected at the firsttime, then that row should be highlighted  and the label of the button should be changed to "Assign Physician".

If the same row is selected again (second time), then the row should be deselected and the label of the button should again be changed to "Add Patients".

At the third time, the row should again be highlighted and the label should be changed to "Assign Physician".

I tried a lot to do the above. But I did not find out how to do this.

PLEASE HELP ME!!!