Move view modifier to separate file

Widgets/DownloadsLiveActivity.swift

@@ -17,21 +17,11 @@ import ActivityKit
 import WidgetKit
 import SwiftUI
 
-struct WidgetBackgroundModifier: ViewModifier {
-    func body(content: Content) -> some View {
-        if #available(iOSApplicationExtension 17.0, *) {
-            content.containerBackground(for: .widget) {
-                Color.widgetBackground
-            }
-            .activityBackgroundTint(Color("WidgetBackground"))
-        } else {
-            content
-                .activityBackgroundTint(Color("WidgetBackground"))
-        }
-    }
-}
-
 struct DownloadsLiveActivity: Widget {
+    var isActivityFullScreen: Bool = false
+//    @Environment(\.isActivityFullscreen) var isActivityFullScreen has a bug, when min iOS is 16
+//    https://developer.apple.com/forums/thread/763594
+    
     var body: some WidgetConfiguration {
         ActivityConfiguration(for: DownloadActivityAttributes.self) { context in
             // Lock screen/banner UI goes here

Widgets/WidgetBackgroundModifier.swift

@@ -0,0 +1,31 @@
+// This file is part of Kiwix for iOS & macOS.
+//
+// Kiwix is free software; you can redistribute it and/or modify it
+// under the terms of the GNU General Public License as published by
+// the Free Software Foundation; either version 3 of the License, or
+// any later version.
+//
+// Kiwix is distributed in the hope that it will be useful, but
+// WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+// General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with Kiwix; If not, see https://www.gnu.org/licenses/.
+
+import SwiftUI
+
+struct WidgetBackgroundModifier: ViewModifier {
+    
+    func body(content: Content) -> some View {
+        if #available(iOSApplicationExtension 17.0, *) {
+            content.containerBackground(for: .widget) {
+                Color.widgetBackground
+            }
+            .activityBackgroundTint(Color("WidgetBackground"))
+        } else {
+            content
+                .activityBackgroundTint(Color("WidgetBackground"))
+        }
+    }
+}