Screen.AvailableHeight

From Xojo Documentation

Read-Only Property (As Integer )
IntegerValue = aScreen.AvailableHeight

Supported for all project types and targets.

The available height (in pixels) of the specified screen, taking into account the menubar and/or the taskbar (Dock on macOS), if present. Use the Screen method to call AvailableHeight. For example, Screen(0).AvailableHeight returns the available height of the main screen.