From Xojo Documentation

Property (As Boolean )
aListBox.AllowResizableColumns = newBooleanValue
BooleanValue = aListBox.AllowResizableColumns

New in 2019r2

Supported for all project types and targets.

If True, the user can resize columns by moving the pointer over a column divider and dragging to the left or right.


When the pointer is over a divider, it changes to an East-West Splitter pointer to indicate that the user can drag the divider. If AllowResizableColumns is False, the pointer does not change its shape.


This example enables the resizable feature.

Me.AllowResizableColumns = True