Improve dialogs a11y (#3094)

* Improve a11y on ios

* Format

* Remove android

* Fix android

src/view/shell/index.tsx

@@ -30,6 +30,7 @@ import {useCloseAnyActiveElement} from '#/state/util'
 import * as notifications from 'lib/notifications/notifications'
 import {Outlet as PortalOutlet} from '#/components/Portal'
 import {MutedWordsDialog} from '#/components/dialogs/MutedWords'
+import {useDialogStateContext} from '#/state/dialogs'
 
 function ShellInner() {
   const isDrawerOpen = useIsDrawerOpen()
@@ -55,6 +56,7 @@ function ShellInner() {
   const closeAnyActiveElement = useCloseAnyActiveElement()
   // start undefined
   const currentAccountDid = React.useRef<string | undefined>(undefined)
+  const {openDialogs} = useDialogStateContext()
 
   React.useEffect(() => {
     let listener = {remove() {}}
@@ -78,9 +80,21 @@ function ShellInner() {
     }
   }, [currentAccount])
 
+  /**
+   * The counterpart to `accessibilityViewIsModal` for Android. This property
+   * applies to the parent of all non-modal views, and prevents TalkBack from
+   * navigating within content beneath an open dialog.
+   *
+   * @see https://reactnative.dev/docs/accessibility#importantforaccessibility-android
+   */
+  const importantForAccessibility =
+    openDialogs.length > 0 ? 'no-hide-descendants' : undefined
+
   return (
     <>
-      <View style={containerPadding}>
+      <View
+        style={containerPadding}
+        importantForAccessibility={importantForAccessibility}>
         <ErrorBoundary>
           <Drawer
             renderDrawerContent={renderDrawerContent}