Exit multi-select mode on back press in sticker management.

app/src/main/java/org/thoughtcrime/securesms/stickers/StickerManagementActivity.kt

@@ -9,6 +9,7 @@ import android.content.Context
 import android.content.Intent
 import android.content.res.Resources
 import android.os.Bundle
+import androidx.activity.compose.BackHandler
 import androidx.activity.compose.setContent
 import androidx.compose.foundation.ExperimentalFoundationApi
 import androidx.compose.foundation.combinedClickable
@@ -286,6 +287,10 @@ fun StickerManagementScreen(
   val pagerState = rememberPagerState(pageCount = { pages.size })
   val coroutineScope = rememberCoroutineScope()
 
+  BackHandler(enabled = uiState.multiSelectEnabled) {
+    onSetMultiSelectModeEnabled(false)
+  }
+
   Scaffold(
     topBar = {
       val isInstalledTabActive = pagerState.currentPage == 1

app/src/main/java/org/thoughtcrime/securesms/stickers/StickerManagementBottomSheet.kt

@@ -7,12 +7,14 @@ package org.thoughtcrime.securesms.stickers
 
 import android.app.Dialog
 import android.os.Bundle
+import androidx.activity.OnBackPressedCallback
 import androidx.compose.foundation.background
 import androidx.compose.foundation.layout.Box
 import androidx.compose.foundation.layout.Column
 import androidx.compose.foundation.layout.fillMaxWidth
 import androidx.compose.material3.MaterialTheme
 import androidx.compose.runtime.Composable
+import androidx.compose.runtime.LaunchedEffect
 import androidx.compose.runtime.getValue
 import androidx.compose.runtime.remember
 import androidx.compose.ui.Alignment
@@ -52,6 +54,12 @@ class StickerManagementBottomSheet : ComposeBottomSheetDialogFragment() {
 
   private val viewModel by viewModel { StickerManagementViewModel() }
 
+  private val multiSelectBackPressCallback = object : OnBackPressedCallback(enabled = false) {
+    override fun handleOnBackPressed() {
+      viewModel.setMultiSelectEnabled(false)
+    }
+  }
+
   override fun onCreate(savedInstanceState: Bundle?) {
     super.onCreate(savedInstanceState)
 
@@ -67,12 +75,18 @@ class StickerManagementBottomSheet : ComposeBottomSheetDialogFragment() {
     return dialog.apply {
       behavior.skipCollapsed = true
       behavior.state = BottomSheetBehavior.STATE_EXPANDED
+      onBackPressedDispatcher.addCallback(multiSelectBackPressCallback)
     }
   }
 
   @Composable
   override fun SheetContent() {
     val uiState by viewModel.uiState.collectAsStateWithLifecycle()
+
+    LaunchedEffect(uiState.multiSelectEnabled) {
+      multiSelectBackPressCallback.isEnabled = uiState.multiSelectEnabled
+    }
+
     Column {
       Box(
         modifier = Modifier