Indicates whether the user can simultaneously hold down the mouse select button and drag the mouse cursor through the selection list. As the mouse cursor passes over an item, the item is highlighted. When the user releases the select button, the highlighted item becomes the selected item.
Data type: LOGICAL
Access: Readable/Writeable
Applies to: SELECTION-LIST widget
In this style of selecting, a user can deselect an item only by selecting another. Once an item is selected, the list cannot revert to its unselected state.
The default value for this attribute is TRUE.
You can set this attribute only before the widget is realized.