remove stupid group, bad implementation, buggy, and not usable

flutter/lib/desktop/widgets/dragable_divider.dart

@@ -1,6 +1,4 @@
 import 'package:flutter/material.dart';
-import 'package:flutter/src/widgets/framework.dart';
-import 'package:flutter/src/widgets/placeholder.dart';
 
 class DraggableDivider extends StatefulWidget {
   final Axis axis;
@@ -28,8 +26,9 @@ class _DraggableDividerState extends State<DraggableDivider> {
   Widget build(BuildContext context) {
     return Listener(
       onPointerMove: (event) {
-        final dl =
-            widget.axis == Axis.horizontal ? event.localDelta.dy : event.localDelta.dx;
+        final dl = widget.axis == Axis.horizontal
+            ? event.localDelta.dy
+            : event.localDelta.dx;
         widget.onPointerMove?.call(dl);
       },
       onPointerHover: (event) => widget.onHover?.call(),

flutter/lib/desktop/widgets/material_mod_popup_menu.dart

@@ -1378,7 +1378,6 @@ class PopupMenuButtonState<T> extends State<PopupMenuButton<T>> {
 
   @override
   Widget build(BuildContext context) {
-    final IconThemeData iconTheme = IconTheme.of(context);
     final bool enableFeedback = widget.enableFeedback ??
         PopupMenuTheme.of(context).enableFeedback ??
         true;

flutter/lib/desktop/widgets/tabbar_widget.dart

@@ -204,6 +204,7 @@ typedef LabelGetter = Rx<String> Function(String key);
 int _lastClickTime =
     DateTime.now().millisecondsSinceEpoch - bind.getDoubleClickTime() - 1000;
 
+// ignore: must_be_immutable
 class DesktopTab extends StatelessWidget {
   final bool showLogo;
   final bool showTitle;