From Xojo Documentation

Property (As Boolean )
aContainerControl.Transparent = newBooleanValue
BooleanValue = aContainerControl.Transparent

Supported for all project types and targets.

If True, the background shows through to the ContainerControl; if False, the ContainerControl is opaque. The default is True.


ContainerControls by default are transparent controls, which means the background shows through. The Transparent property can be set (at design time or runtime) to turn this off/on as needed. An opaque ContainerControl flickers less on Windows, is more optimized on macOS, and on Linux child controls on ContainerControl are clipped properly.


This example turns Transparent off:

Me.Transparent = False