From Xojo Documentation

aListBox.RowSelectionType = newListBox.RowSelectionTypesValue
ListBox.RowSelectionTypesValue = aListBox.RowSelectionType

New in 2019r2

Supported for all project types and targets.

Indicates the type of row selection allowed via mouse gestures.


The type of allowed row selection is set via ListBox.RowSelectionTypes.

The default is single-row selection. If multiple row selection is on, a ListBox will handle Edit ↠ Select All menu item commands by default as long as the Select All menu item is named EditSelectAll.