Selection-Mode
This property activates the ability to select multiple items in the Tree-View. 
The possible values, defined in 
isgui.def, are:
tvsm-single-selection (value 1)  | It’s possible to select a single item.  | 
tvsm-single-interval-selection (value 2)  | It’s possible to select more contiguous items.  | 
tvsm-multiple-interval-selection (value 4)  | It’s possible to select more items, even if they’re not contiguous.   | 
The selection of multiple items is performed by holding CTRL (for multiple interval selection) or SHIFT (for single interval selection) on the keyboard and then use up and down arrow keys or click with the mouse.
The list of the selected items can be retrieved by inquiring the 
Items-Selected property. 
The selection of multiple items is not supported on Tree-Views with the 
Table-View style.
When this property is set either to tvsm-single-interval-selection or to tvsm-multiple-interval-selection, the 
MSG-TV-SELCHANGING event is not fired.
 
Example - Define a tree-view where multiple items can be selected:
... screen section. ...   03 screen-1-tv-1 Tree-View      line 2.7      column 3.4      size 20.8 cells       lines 29.1 cells       color 144      id 2      selection-mode 4      .  |