Support tapping selected sidebar item to scroll to top

Tusker/Screens/Fast Account Switcher/FastAccountSwitcherViewController.xib

@@ -1,9 +1,9 @@
 <?xml version="1.0" encoding="UTF-8"?>
-<document type="com.apple.InterfaceBuilder3.CocoaTouch.XIB" version="3.0" toolsVersion="20037" targetRuntime="iOS.CocoaTouch" propertyAccessControl="none" useAutolayout="YES" useTraitCollections="YES" useSafeAreas="YES" colorMatched="YES">
+<document type="com.apple.InterfaceBuilder3.CocoaTouch.XIB" version="3.0" toolsVersion="32700.99.1234" targetRuntime="iOS.CocoaTouch" propertyAccessControl="none" useAutolayout="YES" useTraitCollections="YES" useSafeAreas="YES" colorMatched="YES">
     <device id="retina6_1" orientation="portrait" appearance="light"/>
     <dependencies>
         <deployment identifier="iOS"/>
-        <plugIn identifier="com.apple.InterfaceBuilder.IBCocoaTouchPlugin" version="20020"/>
+        <plugIn identifier="com.apple.InterfaceBuilder.IBCocoaTouchPlugin" version="22684"/>
         <capability name="Safe area layout guides" minToolsVersion="9.0"/>
         <capability name="documents saved in the Xcode 8 format" minToolsVersion="8.0"/>
     </dependencies>
@@ -32,7 +32,6 @@
                         </subviews>
                         <constraints>
                             <constraint firstItem="lYU-Bb-3Wi" firstAttribute="top" secondItem="1Gd-Da-Vab" secondAttribute="topMargin" placeholder="YES" id="KQs-d5-U3f"/>
-                            <constraint firstAttribute="trailing" secondItem="lYU-Bb-3Wi" secondAttribute="trailingMargin" constant="8" id="UZh-xR-XVt"/>
                             <constraint firstAttribute="bottomMargin" secondItem="lYU-Bb-3Wi" secondAttribute="bottom" placeholder="YES" id="j6f-r5-NNI"/>
                             <constraint firstItem="lYU-Bb-3Wi" firstAttribute="leading" secondItem="1Gd-Da-Vab" secondAttribute="leading" constant="8" id="sae-ga-MGE"/>
                         </constraints>
@@ -47,6 +46,7 @@
                 <constraint firstItem="5fd-Ni-Owc" firstAttribute="leading" secondItem="i5M-Pr-FkT" secondAttribute="leading" id="phf-PC-bdH"/>
                 <constraint firstItem="5fd-Ni-Owc" firstAttribute="top" secondItem="i5M-Pr-FkT" secondAttribute="top" id="rz7-cQ-PIC"/>
                 <constraint firstAttribute="bottom" secondItem="5fd-Ni-Owc" secondAttribute="bottom" id="sHl-iD-kGi"/>
+                <constraint firstItem="fnl-2z-Ty3" firstAttribute="trailing" secondItem="lYU-Bb-3Wi" secondAttribute="trailing" constant="8" id="snX-cx-wq6"/>
             </constraints>
             <point key="canvasLocation" x="140.57971014492756" y="144.64285714285714"/>
         </view>

Tusker/Screens/Main/MainSidebarViewController.swift

@@ -15,6 +15,7 @@ protocol MainSidebarViewControllerDelegate: AnyObject {
     func sidebarRequestPresentCompose(_ sidebarViewController: MainSidebarViewController)
     func sidebar(_ sidebarViewController: MainSidebarViewController, didSelectItem item: MainSidebarViewController.Item)
     func sidebar(_ sidebarViewController: MainSidebarViewController, showViewController viewController: UIViewController)
+    func sidebar(_ sidebarViewController: MainSidebarViewController, scrollToTopFor item: MainSidebarViewController.Item)
 }
 
 class MainSidebarViewController: UIViewController {
@@ -451,7 +452,9 @@ extension MainSidebarViewController: UICollectionViewDelegate {
             return
         }
         itemLastSelectedTimestamps[item] = Date()
-        if [MainSidebarViewController.Item.tab(.compose), .addList, .addSavedHashtag, .addSavedInstance].contains(item) {
+        if previouslySelectedItem == item {
+            sidebarDelegate?.sidebar(self, scrollToTopFor: item)
+        } else if [MainSidebarViewController.Item.tab(.compose), .addList, .addSavedHashtag, .addSavedInstance].contains(item) {
             if let previous = previouslySelectedItem, let indexPath = dataSource.indexPath(for: previous) {
                 collectionView.selectItem(at: indexPath, animated: false, scrollPosition: .centeredVertically)
             }

Tusker/Screens/Main/MainSplitViewController.swift

@@ -478,6 +478,10 @@ extension MainSplitViewController: MainSidebarViewControllerDelegate {
         }
         secondaryNavController.viewControllers = [viewController]
     }
+    
+    func sidebar(_ sidebarViewController: MainSidebarViewController, scrollToTopFor item: MainSidebarViewController.Item) {
+        (secondaryNavController as? TabBarScrollableViewController)?.tabBarScrollToTop()
+    }
 }
 
 fileprivate extension MainSidebarViewController.Item {

Tusker/Screens/Main/MainTabBarViewController.swift

@@ -241,6 +241,7 @@ extension MainTabBarViewController {
 #if !os(visionOS)
 extension MainTabBarViewController: FastAccountSwitcherViewControllerDelegate {
     func fastAccountSwitcherAddToViewHierarchy(_ fastAccountSwitcher: FastAccountSwitcherViewController) {
+        fastAccountSwitcher.view.translatesAutoresizingMaskIntoConstraints = false
         view.addSubview(fastAccountSwitcher.view)
         NSLayoutConstraint.activate([
             fastAccountSwitcher.accountsStack.bottomAnchor.constraint(equalTo: fastAccountSwitcher.view.bottomAnchor),
@@ -249,6 +250,10 @@ extension MainTabBarViewController: FastAccountSwitcherViewControllerDelegate {
             fastAccountSwitcher.view.trailingAnchor.constraint(equalTo: view.trailingAnchor),
             fastAccountSwitcher.view.topAnchor.constraint(equalTo: view.topAnchor),
             fastAccountSwitcher.view.bottomAnchor.constraint(equalTo: tabBar.topAnchor),
+            
+            // The safe area insets don't automatically propagate for some reason, so do it ourselves.
+            fastAccountSwitcher.view.safeAreaLayoutGuide.leadingAnchor.constraint(equalTo: view.safeAreaLayoutGuide.leadingAnchor),
+            fastAccountSwitcher.view.safeAreaLayoutGuide.trailingAnchor.constraint(equalTo: view.safeAreaLayoutGuide.trailingAnchor),
         ])
     }
     

Tusker/Screens/Utilities/SplitNavigationController.swift

@@ -258,6 +258,12 @@ class SplitNavigationController: UIViewController {
     }
 }
 
+extension SplitNavigationController: TabBarScrollableViewController {
+    func tabBarScrollToTop() {
+        (viewControllers.last as? TabBarScrollableViewController)?.tabBarScrollToTop()
+    }
+}
+
 extension SplitNavigationController: StatusBarTappableViewController {
     func handleStatusBarTapped(xPosition: CGFloat) -> StatusBarTapActionResult {
         let vcs = viewControllers