From Xojo Documentation

Read-Only Property (As Boolean )
BooleanValue = aWebUIControl.LockHorizontal

New in 2020r1

Supported for all project types and targets.

LockHorizontal overrides LockLeft and LockRight. It allows you to proportionally lock a control's position to the center of its parent control (or web page).


For example, if you place a control in the center of the page and sets both LockHorizontal and LockVertical, the control will stay in the center of the page.