allow copying messages when on desktop without mobile mode on

lib/widgets/html/html.dart

@@ -1,7 +1,10 @@
+import "dart:io";
+
 import "package:fast_immutable_collections/fast_immutable_collections.dart";
 import "package:material_ui/material_ui.dart";
 import "package:flutter_riverpod/flutter_riverpod.dart";
 import "package:flutter_widget_from_html_core/flutter_widget_from_html_core.dart";
+import "package:nexus/controllers/settings.dart";
 import "package:nexus/helpers/extensions/link_to_mention.dart";
 import "package:nexus/helpers/launch_helper.dart";
 import "package:nexus/helpers/mxc_image.dart";
@@ -18,9 +21,9 @@ class const Html(
   super.key,
 }) extends ConsumerWidget {
   @override
-  Widget build(BuildContext context, WidgetRef ref) =>
+  Widget build(BuildContext context, WidgetRef ref) {
     // needed until https://github.com/daohoangson/flutter_widget_from_html/issues/1618 is resolved
-      MaterialUiCompatibilityBridge(
+    final htmlWidget = MaterialUiCompatibilityBridge(
       child: HtmlWidget(
         html,
         buildAsync: false,
@@ -146,4 +149,24 @@ class const Html(
             ref.watch(LaunchHelper.provider).launchUrl(.parse(url)),
       ),
     );
+
+    final shouldBeSelectable =
+        ref
+            .watch(SettingsController.provider)
+            .when(
+              data: (data) => !data.linuxMobileMode,
+              error: (_, _) => false,
+              loading: () => false,
+            ) ||
+        Platform.isIOS ||
+        Platform.isAndroid;
+    return shouldBeSelectable
+        ? SelectableRegion(
+            contextMenuBuilder: (context, selectableRegionState) =>
+                Text("data"),
+            selectionControls: materialTextSelectionControls,
+            child: htmlWidget,
+          )
+        : htmlWidget;
+  }
 }