Items & Overflow

Items are declared on the page, not on the navigation page — the same shape Page.ToolbarItems already has, so a page can be moved between hosts without any of it changing.

<ContentPage xmlns:shiny="http://shiny.net/maui/controls" Title="Inbox">

    <shiny:ShinyNav.LeftItems>
        <shiny:NavBarItem Icon="menu" Command="{Binding OpenDrawerCommand}" />
    </shiny:ShinyNav.LeftItems>

    <shiny:ShinyNav.RightItems>
        <shiny:NavBarItem Icon="search" Command="{Binding SearchCommand}" />
        <shiny:NavBarItem Icon="bell" Badge="3" Command="{Binding AlertsCommand}" />
        <shiny:NavBarItem Text="Mark all read" Icon="check" Order="Secondary" Command="{Binding MarkAllCommand}" />
        <shiny:NavBarItem IsSeparator="True" Order="Secondary" />
        <shiny:NavBarItem Text="Delete all" Icon="trash" Order="Secondary" IsDestructive="True" Command="{Binding DeleteCommand}" />
    </shiny:ShinyNav.RightItems>
</ContentPage>

NavBarItem is a ToolbarItem

It derives from ToolbarItem, so everything you already know keeps its meaning:

Inherited	Meaning
Text	the label
IconImageSource	a bitmap or font glyph
Command / CommandParameter	run on tap
Clicked	raised on tap, after the command
IsEnabled	a disabled item is dimmed and untappable
IsDestructive	drawn in the theme’s error colour
Order	Default/Primary on the bar, Secondary in the overflow menu
Priority	orders items within their side

And it adds:

Added	Meaning
Icon	a built-in motion icon name — search, bell, trash…
IconSource / IconPathData / Motion	explicit motion artwork, a raw 24×24 SVG path, and which motion it plays
IconColor	tints this item’s motion artwork
Badge / BadgeColor	a corner badge — "" is a dot, null is nothing
Display	Auto (icon when there is one), Icon, Text, IconAndText
IsVisible	hides the item without removing it from the collection
IsSeparator	a divider — in the menu only
Tag	whatever identifies the item to your handler; Text is not unique

Because both collections are typed IList<ToolbarItem>, a plain <ToolbarItem> drops into either one unchanged.

Your existing toolbar already works

A page’s own Page.ToolbarItems are drawn on the right automatically, ahead of anything in ShinyNav.RightItems. Adopting the page never means rewriting a toolbar — the left side is purely additive.

What overflows

Two rules, in this order:

1. Order="Secondary" folds an item into that side’s overflow menu, however much room the bar has.
2. Anything past MaxVisibleItems (default 3, per side) folds in behind it.

Set MaxVisibleItems="0" (or any value ≤ 0) for no limit, and then only Secondary items overflow. Each side gets its own overflow button, and a side with nothing to overflow gets none.

OverflowIcon names a motion icon to draw instead of the default three-dot glyph. MenuTemplate replaces the card’s contents wholesale while the bar keeps the backdrop, the anchoring and the open/close animation; its binding context is the collection that overflowed.

Open a menu yourself:

ShinyNavigationPage.GetNavBar(page)?.OpenMenu(NavBarSide.Right);

Binding to items

An attached-property collection has no parent, so nothing would ordinarily hand its items a binding context and every {Binding} on one would silently resolve against null. ShinyNavigationPage seeds the page’s binding context onto them as an inherited context, so bindings work and an explicit BindingContext on an item still wins.

Item properties are bindable, so nothing about the collection has to change for the bar to redraw:

// the bar rebuilds itself off the item's own PropertyChanged
alertsItem.Badge = unread == 0 ? null : unread.ToString();

Reacting to a tap

Three ways, all live at once:

item.Command  = new Command(...);          // on the item
item.Clicked += (s, e) => { ... };         // on the item
nav.NavBarItemInvoked += (s, e) => { ... }; // on the navigation page, for any of its bars
bar.ItemInvoked        += (s, e) => { ... }; // on one bar

The bar invokes an item through IMenuItemController.Activate() — the same call a native toolbar makes — so an item behaves identically whether it was drawn here or by the platform.