TreeView controls
When HasButtons is enabled, PowerBuilder displays + and - buttons next to parent items. The buttons indicate whether an item is expanded (-) or collapsed (+).
To enable the display of buttons:
Select the HasButtons check box on the General page of the control’s Properties view.
The HasButtons property takes a boolean value. The following line specifies that PowerBuilder will display + and - buttons in a TreeView:
tv_1.HasButtons = TRUE
