property Thumbnail.SingleSel as Boolean
Retrieves or sets a value that indicates whether the control supports single or multiple selection.

TypeDescription
Boolean A Boolean expression that specifies whether the user can select a single thumbnail or more.
By default, the SingleSel property is true, which indicates that only one thumbnail can be selected at any time. The SingleSel property Retrieves or sets a value that indicates whether the control supports single or multiple selection. The Select property gets or sets the file(s)/thumbnail(s) selected. If SingleSel property is False, the user can select mutliple-thumbnail(s) using the CTRL key.