From Xojo Documentation
The bevel style. The Bevel property affects the appearance and in some cases the shape of the BevelButton.
The following are the bevel styles.
|3||Rounded bevel (macOS only)|
|4||No Bevel (Windows only)|
|5||Round (macOS only)|
|6||Large Round (macOS only)|
|7||Disclosure (macOS only)|
The macOS-only bevel styles appear as the Small Bevel style on other platforms.
Bevel styles and appearance varies in general between operating systems and sometimes between versions of operating systems.
This example sets the Bevel property to Round.