From Xojo Documentation
| This property is only available on the Windows platform.
For cross-platform compatibility, use ＃If...＃Endif with the Target... specifiers to make sure you will not attempt to use this property on an incompatible platform.
Use this property to set the transparency of this control. If True, the control will overlay transparently on top of a graphic. For example if you overlay a Label on top of a Canvas/Image then if Transparent is true, the text will overlay transparently (i.e. the background shows through). A non-Transparent Label control will not cause any flicker.
This property applies only to Windows. On macOS and Linux, a Label will always render transparently regardless of this property's value.