From Xojo Documentation
Property (As Boolean )
| This property is only available on macOS and Linux platforms.
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.
This property does nothing on Windows so use MenuItem.RemoveMenuAt instead.
This code is in the Open event of the main window:
EditFind.Visible = False