Disabled menu items shouldn't close the dropdown when clicked

[BradFeng02]

Right now, if you have a MenuItem with IsEnabled="false", it's grayed out as expected. But when you click on it, the dropdown menu still closes. This doesn't match other UIs (like with Chrome's context menu or Visual Studio's menu, for example).

edit: it only happens with dropdowns from a top level menu item and not the flyouts for subitems

[simonhaines]

If no-one is working on this, I'd like to take this on. A good reason for a deep dive into the event system.

[maxkatz6]

@simonhaines nobody from core team has started this task yet, so it's free.
I believe this condition should be updated https://github.com/AvaloniaUI/Avalonia/blob/master/src/Avalonia.Controls/Platform/DefaultMenuInteractionHandler.cs#L381
Or maybe this one https://github.com/AvaloniaUI/Avalonia/blob/master/src/Avalonia.Controls/Platform/DefaultMenuInteractionHandler.cs#L456
Also worth to check how it works with keyboard focus.

[simonhaines]

@maxkatz6 the first condition is where I am focusing effort, but there are some subtleties, as always. Currently the popup closes when disabled elements are clicked, but also separators, and clicks in the client area of the popup outside enabled menu items.

The simplest thing I have done that works is change the first condition to:

if (item.IsTopLevel && e.Source is not Border)
{
    CloseMenu(item);
}

This is a quick test to see if the pointer press event is bubbled from the Popup and not the top-level menu item (so that clicking the top-level item itself will close the pop-up), but I think this creates a coupling between the layout and the interaction logic that can easily break. I am exploring more reliable options.