From Xojo Documentation
| This item was deprecated in version 2019r2.
Please use MenuItem.HasMacOptionKey as a replacement.
| This property is only available on the macOS 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.
The Option key on Macintosh. This property is Macintosh-only. If selected, the Option key must be held down while pressing the value of the Key property to trigger the event handler of the MenuItem.
Use MenuItem.KeyboardShortCut to change this value at runtime.