[BUG] CloseOnBackground not honored on iOS

Description

Title: IDialogService popup with CloseOnBackgroundTapped="True" does not dismiss on iOS (Mopups container missing the dismiss mask)

---

This is the iOS counterpart to #3322 ("CloseOnBackgroundTapped not honored"),
which was closed as fixed on the private feed. On Prism.Plugin.Popups.Maui
9.1.33-pre the flag is now plumbed correctly, but the popup still does not
dismiss on background tap on iOS. I traced it to the container layout.

Environment

• Prism.DryIoc.Maui 9.1.111-pre, Prism.Maui 9.1.86-pre
• Prism.Plugin.Popups.Maui 9.1.33-pre, Mopups 1.3.4
• .NET 10, net10.0-ios, iOS 26 simulator + device

Root cause

The flag is read and applied — Prism.Maui's DialogServiceBase reads
DialogLayout.GetCloseOnBackgroundTapped(view) and passes it to
PopupDialogContainer.ConfigureLayout, which sets
((PopupPage)this).CloseWhenBackgroundIsClicked = hideOnBackgroundTapped.

The problem is the layout. PopupDialogContainer.GetContentLayout builds a
screen-filling AbsoluteLayout with the dialog as a centered child, then
leans on Mopups' CloseWhenBackgroundIsClicked to detect a background tap. But
that mechanism only fires for a tap outside the content frame — and the
AbsoluteLayout fills the whole page, so on iOS every tap is "inside content"
and the background tap is never recognized.

By contrast, Prism.Maui's default container DialogContainerPage does not
rely on Mopups detection — it adds a BoxView mask with a
TapGestureRecognizer bound to the dismiss command. PopupDialogContainer is
simply missing that mask.

Suggested fix

Give PopupDialogContainer the same mask + gesture that DialogContainerPage
already uses, instead of depending on CloseWhenBackgroundIsClicked. A minimal
override that does exactly this (drop-in proof, in the repro):

protected override View GetContentLayout(Page currentPage, View dialogView,
    bool hideOnBackgroundTapped, ICommand dismissCommand, IDialogParameters parameters)
{
    var content = base.GetContentLayout(currentPage, dialogView, hideOnBackgroundTapped,
        dismissCommand, parameters);

    if (hideOnBackgroundTapped && content is AbsoluteLayout layout)
    {
        var scrim = new BoxView { Color = Colors.Transparent };
        AbsoluteLayout.SetLayoutFlags(scrim, AbsoluteLayoutFlags.All);
        AbsoluteLayout.SetLayoutBounds(scrim, new Rect(0, 0, 1, 1));
        scrim.GestureRecognizers.Add(new TapGestureRecognizer { Command = dismissCommand });
        layout.Children.Insert(0, scrim); // behind the dialog
    }

    return content;
}

Steps to Reproduce

Repro

Minimal repo: [prism-popup-dismiss-repro]

1. UsePrism(... .ConfigureMopupDialogs() ...), register a dialog whose root sets
   prism:DialogLayout.CloseOnBackgroundTapped="True".
2. IDialogService.ShowDialog(...) it on iOS.
3. Tap the dimmed background.

Expected: dialog dismisses. Actual: dialog stays open.

Platform with bug

.NET MAUI

Affected platforms

iOS

Did you find any workaround?

No response

Relevant log output

Start by locating PopupDialogContainer.GetContentLayout and compare it with the mask and tap gesture used by DialogContainerPage. Reproduce the dialog on iOS from the linked repro, then verify that tapping the dimmed background dismisses the popup while taps on the dialog content do not.