From Xojo Documentation

Read-Only Property (As Integer )
IntegerValue = aDesktopDisplay.AvailableLeft

New in 2021r3

Supported for all project types and targets.

The starting position of the left edge of the specified display. This would be zero unless, for example, the user had placed the taskbar (Windows and Linux) or the Dock (macOS) on the left.


Use the DesktopDisplay.DisplayAt method to call AvailableLeft. For example, DesktopDisplay(0).AvailableLeft returns the available left number of points of the main display.