ListColumn.UserResizable

From Xojo Documentation

Property (As Boolean )
aListColumn.UserResizable = newBooleanValue
or
BooleanValue = aListColumn.UserResizable

Supported for all project types and targets.

True if the column is resizable; the default is False.

Example

The following line in the Open event of a ListBox makes all the columns in the ListBox resizable:

Me.Column(-1).UserResizable = True