NSScrollExample (Xamarin documentation) does not work

[GT85]

MacOS Mojave 10.14.6 dark mode, VS for Mac Community 8.5.4

Hello.
Running this app displays a small black window (500 x 250 ?) with 2 buttons and no scroll bars. Extending this window add gray surface up and right.
Could you please fix this bug or explain my error ?
Regards,
Gilbert

[chamons]

This is what i see:

If you move the mouse over the lower left, you should see the scroll view.

[chamons]

Depending on your setting here:

In System Settings -> General you may see different SO default draws.

[GT85]

Hi Chris.
OK. That works with 2 fingers on the trackpad. Also with the mouse if I set "Always".
Thanks,
Gilbert