group fab; prevent empty filter grid scroll

lib/widgets/dialogs/pick_dialogs/album_pick_page.dart

@@ -18,7 +18,6 @@ import 'package:aves/view/view.dart';
 import 'package:aves/widgets/common/action_mixins/feedback.dart';
 import 'package:aves/widgets/common/action_mixins/vault_aware.dart';
 import 'package:aves/widgets/common/extensions/build_context.dart';
-import 'package:aves/widgets/common/identity/aves_fab.dart';
 import 'package:aves/widgets/common/identity/aves_filter_chip.dart';
 import 'package:aves/widgets/common/identity/buttons/captioned_button.dart';
 import 'package:aves/widgets/common/identity/empty.dart';
@@ -190,8 +189,7 @@ class _AlbumPickPageState extends State<_AlbumPickPage> with FeedbackMixin, Vaul
 
   Widget? _buildFab(BuildContext context) {
     return isPickingGroup
-        ? AvesFab(
+        ? FloatingActionButton.extended(
-            tooltip: context.l10n.groupPickerUseThisGroupButton,
             onPressed: () {
               final groupUri = context.read<FilterGroupNotifier>().value;
               final filter = groupUri != null ? albumGrouping.uriToFilter(groupUri) : AlbumGroupFilter.root;
@@ -199,6 +197,8 @@ class _AlbumPickPageState extends State<_AlbumPickPage> with FeedbackMixin, Vaul
                 _pickFilter(context, filter);
               }
             },
+            icon: const Icon(AIcons.apply),
+            label: Text(context.l10n.groupPickerUseThisGroupButton),
           )
         : null;
   }

lib/widgets/filter_grids/common/filter_grid_page.dart

@@ -18,6 +18,7 @@ import 'package:aves/widgets/common/basic/scaffold.dart';
 import 'package:aves/widgets/common/behaviour/pop/double_back.dart';
 import 'package:aves/widgets/common/behaviour/pop/scope.dart';
 import 'package:aves/widgets/common/behaviour/pop/tv_navigation.dart';
+import 'package:aves/widgets/common/behaviour/sloppy_scroll_physics.dart';
 import 'package:aves/widgets/common/extensions/build_context.dart';
 import 'package:aves/widgets/common/extensions/media_query.dart';
 import 'package:aves/widgets/common/grid/item_tracker.dart';
@@ -683,30 +684,37 @@ class _FilterScrollView<T extends CollectionFilter> extends StatelessWidget {
   }
 
   Widget _buildScrollView(BuildContext context) {
+    return Selector<SectionedListLayout<FilterGridItem<T>>, bool>(
+      selector: (context, layout) => layout.sections.isEmpty,
+      builder: (context, isEmpty, child) {
         return CustomScrollView(
           key: scrollableKey,
           controller: scrollController,
+          // workaround to prevent scrolling the app bar away
+          // when there is no content and we use `SliverFillRemaining`
+          physics: isEmpty
+              ? const NeverScrollableScrollPhysics()
+              : SloppyScrollPhysics(
+                  gestureSettings: MediaQuery.gestureSettingsOf(context),
+                  parent: const AlwaysScrollableScrollPhysics(),
+                ),
           slivers: [
             appBar,
             AnimationLimiter(
               key: ValueKey(context.select<FilterGroupNotifier?, Uri?>((v) => v?.value)),
-          child: Selector<SectionedListLayout<FilterGridItem<T>>, bool>(
+              child: isEmpty
-            selector: (context, layout) => layout.sections.isEmpty,
-            builder: (context, empty, child) {
-              return empty
-                  // TODO TLAD [nested] prevent scrolling when empty (cf CollectionPage)
                   ? SliverFillRemaining(
                       hasScrollBody: false,
                       child: emptyBuilder(),
                     )
-                  : SectionedListSliver<FilterGridItem<T>>();
+                  : SectionedListSliver<FilterGridItem<T>>(),
-            },
-          ),
             ),
             const NavBarPaddingSliver(),
             const BottomPaddingSliver(),
             const TvTileGridBottomPaddingSliver(),
           ],
         );
+      },
+    );
   }
 }