feat(master-detail): allow inserting spacers and dividers

[jpnurmi]

A separate bottom bar works fine for about or settings dialogs and similar, but gets clumsy if one wants to have normal master tiles at the bottom. This PR makes it possible for YaruMasterDetailPage.tileBuilder to return spacers (and dividers) to make it possible to categorize master list items in any way desired.

final pages = <({WidgetBuilder tile, WidgetBuilder page})>[
  (
    tile: (_) => const YaruMasterTile(title: Text('Foo')),
    page: (_) => const Center(child: Text('Foo')),
  ),
  (
    tile: (_) => const YaruMasterTile(title: Text('Bar')),
    page: (_) => const Center(child: Text('Bar')),
  ),
  (
    tile: (_) => const YaruMasterTile(title: Text('Baz')),
    page: (_) => const Center(child: Text('Baz')),
  ),
  (
    tile: (_) => const YaruMasterTile(title: Text('Qux')),
    page: (_) => const Center(child: Text('Qux')),
  ),
  (
    tile: (_) => const Spacer(),
    page: (_) => const SizedBox.shrink(),
  ),
  (
    tile: (_) => const Divider(height: 1),
    page: (_) => const SizedBox.shrink(),
  ),
  (
    tile: (_) => const YaruMasterTile(title: Text('Manage')),
    page: (_) => const Center(child: Text('Manage')),
  ),
  (
    tile: (_) => const YaruMasterTile(title: Text('About')),
    page: (_) => const Center(child: Text('About')),
  ),
];

return Scaffold(
  appBar: const YaruWindowTitleBar(title: Text('YaruMasterDetailPage')),
  body: YaruMasterDetailPage(
    length: pages.length,
    tileBuilder: (context, index, selected, availableWidth) =>
        pages[index].tile(context),
    pageBuilder: (context, index) => pages[index].page(context),
  ),
);

[Feichtmeier]

ah very nice! Can also use this in musicpod xD currently doing some kung fu to count the element then wrapping it in column with divider -.-

[jpnurmi]

It should work fine with multiple sections/dividers too 👍

[Jupi007]

Awesome! 😃