From Xojo Documentation
Supported PlatformsProject Types: Desktop Platforms: macOS, Windows, Linux
|result||Boolean||True if the contextual mouse button has been clicked and False if it was not.|
A contextual click varies depending on platform and user settings. Most often it is done by right-clicking the mouse. On macOS, a contextual click is also triggered by holding the control key down while left clicking.
IsContextualClick is useful in the MouseDown event to check for a contextual click when you are not intending to display a menu.
To display an existing menu, you should use the Clone method as in this example: