We can now discard the warning and wait until the authors of these packages deal with the new changes in flutter 3 to solve the problem. The developers now catching up for those changes and these should be new versions of the affected packages soon.

https://stackoverflow.com/questions/72239258/flutter-warning-operand-of-null-aware-operation-has-type-widgetsbinding

/C:/tools/flutter_sdk/.pub-cache/hosted/pub.dartlang.org/animated_custom_dropdown-1.2.1/lib/dropdown_overlay.dart:57:20: Warning: Operand of null-aware operation '?.' has type 'WidgetsBinding' which excludes null.

'WidgetsBinding' is from 'package:flutter/src/widgets/binding.dart' ('/C:/tools/flutter_sdk/packages/flutter/lib/src/widgets/binding.dart'). package:flutter/…/widgets/binding.dart:1

WidgetsBinding.instance?.addPostFrameCallback((_) {

I am using valuelistenable builder and once a value from dropdown is selected i changed the drop down to text but this is what i additionally get when onChange is called

======== Exception caught by widgets library ======================================================= The following assertion was thrown while finalizing the widget tree: _AnimatedSectionState#c115a(ticker active) was disposed with an active Ticker.

_AnimatedSectionState created a Ticker via its SingleTickerProviderStateMixin, but at the time dispose() was called on the mixin, that Ticker was still active. The Ticker must be disposed before calling super.dispose().

Tickers used by AnimationControllers should be disposed by calling dispose() on the AnimationController itself. Otherwise, the ticker will leak.

The offending ticker was: Ticker(created by _AnimatedSectionState#c115a) The stack trace when the Ticker was actually created was: #0 new Ticker. (package:flutter/src/scheduler/ticker.dart:67:40) #1 new Ticker (package:flutter/src/scheduler/ticker.dart:69:6) #2 SingleTickerProviderStateMixin.createTicker (package:flutter/src/widgets/ticker_provider.dart:198:15) #3 new AnimationController (package:flutter/src/animation/animation_controller.dart:246:21) #4 _AnimatedSectionState.prepareAnimations (package:animated_custom_dropdown/animated_section.dart:33:22) #5 _AnimatedSectionState.initState (package:animated_custom_dropdown/animated_section.dart:28:5) #6 StatefulElement._firstBuild (package:flutter/src/widgets/framework.dart:4893:57) #7 ComponentElement.mount (package:flutter/src/widgets/framework.dart:4729:5) ... Normal element mounting (64 frames) #71 Element.inflateWidget (package:flutter/src/widgets/framework.dart:3790:14) #72 MultiChildRenderObjectElement.inflateWidget (package:flutter/src/widgets/framework.dart:6422:36) #73 MultiChildRenderObjectElement.mount (package:flutter/src/widgets/framework.dart:6433:32) ... Normal element mounting (63 frames) #136 Element.inflateWidget (package:flutter/src/widgets/framework.dart:3790:14) #137 MultiChildRenderObjectElement.inflateWidget (package:flutter/src/widgets/framework.dart:6422:36) #138 Element.updateChild (package:flutter/src/widgets/framework.dart:3540:18) #139 RenderObjectElement.updateChildren (package:flutter/src/widgets/framework.dart:5845:32) #140 MultiChildRenderObjectElement.update (package:flutter/src/widgets/framework.dart:6445:17) #141 Element.updateChild (package:flutter/src/widgets/framework.dart:3501:15) #142 ComponentElement.performRebuild (package:flutter/src/widgets/framework.dart:4780:16) #143 StatefulElement.performRebuild (package:flutter/src/widgets/framework.dart:4928:11) #144 Element.rebuild (package:flutter/src/widgets/framework.dart:4477:5) #145 BuildOwner.buildScope (package:flutter/src/widgets/framework.dart:2659:19) #146 WidgetsBinding.drawFrame (package:flutter/src/widgets/binding.dart:882:21) #147 RendererBinding._handlePersistentFrameCallback (package:flutter/src/rendering/binding.dart:363:5) #148 SchedulerBinding._invokeFrameCallback (package:flutter/src/scheduler/binding.dart:1144:15) #149 SchedulerBinding.handleDrawFrame (package:flutter/src/scheduler/binding.dart:1081:9) #150 SchedulerBinding._handleDrawFrame (package:flutter/src/scheduler/binding.dart:995:5) #154 _invoke (dart:ui/hooks.dart:151:10) #155 PlatformDispatcher._drawFrame (dart:ui/platform_dispatcher.dart:308:5) #156 _drawFrame (dart:ui/hooks.dart:115:31) (elided 3 frames from dart:async)

When the exception was thrown, this was the stack: #0 SingleTickerProviderStateMixin.dispose. (package:flutter/src/widgets/ticker_provider.dart:209:7) #1 SingleTickerProviderStateMixin.dispose (package:flutter/src/widgets/ticker_provider.dart:223:6) #2 _AnimatedSectionState.dispose (package:animated_custom_dropdown/animated_section.dart:64:11) #3 StatefulElement.unmount (package:flutter/src/widgets/framework.dart:4983:11) #4 _InactiveElements._unmount (package:flutter/src/widgets/framework.dart:1926:13) #5 _InactiveElements._unmount. (package:flutter/src/widgets/framework.dart:1924:7) #6 ComponentElement.visitChildren (package:flutter/src/widgets/framework.dart:4807:14) #7 _InactiveElements._unmount (package:flutter/src/widgets/framework.dart:1922:13) #8 _InactiveElements._unmount. (package:flutter/src/widgets/framework.dart:1924:7) #9 ComponentElement.visitChildren (package:flutter/src/widgets/framework.dart:4807:14) #10 _InactiveElements._unmount (package:flutter/src/widgets/framework.dart:1922:13) #11 _InactiveElements._unmount. (package:flutter/src/widgets/framework.dart:1924:7) #12 SingleChildRenderObjectElement.visitChildren (package:flutter/src/widgets/framework.dart:6271:14) #13 _InactiveElements._unmount (package:flutter/src/widgets/framework.dart:1922:13) #14 _InactiveElements._unmount. (package:flutter/src/widgets/framework.dart:1924:7) #15 ComponentElement.visitChildren (package:flutter/src/widgets/framework.dart:4807:14) #16 _InactiveElements._unmount (package:flutter/src/widgets/framework.dart:1922:13) #17 _InactiveElements._unmount. (package:flutter/src/widgets/framework.dart:1924:7) #18 SingleChildRenderObjectElement.visitChildren (package:flutter/src/widgets/framework.dart:6271:14) #19 _InactiveElements._unmount (package:flutter/src/widgets/framework.dart:1922:13) #20 _InactiveElements._unmount. (package:flutter/src/widgets/framework.dart:1924:7) #21 ComponentElement.visitChildren (package:flutter/src/widgets/framework.dart:4807:14) #22 _InactiveElements._unmount (package:flutter/src/widgets/framework.dart:1922:13) #23 _InactiveElements._unmount. (package:flutter/src/widgets/framework.dart:1924:7) #24 ComponentElement.visitChildren (package:flutter/src/widgets/framework.dart:4807:14) #25 _InactiveElements._unmount (package:flutter/src/widgets/framework.dart:1922:13) #26 _InactiveElements._unmount. (package:flutter/src/widgets/framework.dart:1924:7) #27 SingleChildRenderObjectElement.visitChildren (package:flutter/src/widgets/framework.dart:6271:14) #28 _InactiveElements._unmount (package:flutter/src/widgets/framework.dart:1922:13) #29 _InactiveElements._unmount. (package:flutter/src/widgets/framework.dart:1924:7) #30 SingleChildRenderObjectElement.visitChildren (package:flutter/src/widgets/framework.dart:6271:14) #31 _InactiveElements._unmount (package:flutter/src/widgets/framework.dart:1922:13) #32 _InactiveElements._unmount. (package:flutter/src/widgets/framework.dart:1924:7) #33 ComponentElement.visitChildren (package:flutter/src/widgets/framework.dart:4807:14) #34 _InactiveElements._unmount (package:flutter/src/widgets/framework.dart:1922:13) #35 _InactiveElements._unmount. (package:flutter/src/widgets/framework.dart:1924:7) #36 SingleChildRenderObjectElement.visitChildren (package:flutter/src/widgets/framework.dart:6271:14) #37 _InactiveElements._unmount (package:flutter/src/widgets/framework.dart:1922:13) #38 _InactiveElements._unmount. (package:flutter/src/widgets/framework.dart:1924:7) #39 ComponentElement.visitChildren (package:flutter/src/widgets/framework.dart:4807:14) #40 _InactiveElements._unmount (package:flutter/src/widgets/framework.dart:1922:13) #41 _InactiveElements._unmount. (package:flutter/src/widgets/framework.dart:1924:7) #42 MultiChildRenderObjectElement.visitChildren (package:flutter/src/widgets/framework.dart:6386:16) #43 _InactiveElements._unmount (package:flutter/src/widgets/framework.dart:1922:13) #44 _InactiveElements._unmount. (package:flutter/src/widgets/framework.dart:1924:7) #45 SingleChildRenderObjectElement.visitChildren (package:flutter/src/widgets/framework.dart:6271:14) #46 _InactiveElements._unmount (package:flutter/src/widgets/framework.dart:1922:13) #47 _InactiveElements._unmount. (package:flutter/src/widgets/framework.dart:1924:7) #48 SingleChildRenderObjectElement.visitChildren (package:flutter/src/widgets/framework.dart:6271:14) #49 _InactiveElements._unmount (package:flutter/src/widgets/framework.dart:1922:13) #50 _InactiveElements._unmount. (package:flutter/src/widgets/framework.dart:1924:7) #51 ComponentElement.visitChildren (package:flutter/src/widgets/framework.dart:4807:14) #52 _InactiveElements._unmount (package:flutter/src/widgets/framework.dart:1922:13) #53 _InactiveElements._unmount. (package:flutter/src/widgets/framework.dart:1924:7) #54 SingleChildRenderObjectElement.visitChildren (package:flutter/src/widgets/framework.dart:6271:14) #55 _InactiveElements._unmount (package:flutter/src/widgets/framework.dart:1922:13) #56 _InactiveElements._unmount. (package:flutter/src/widgets/framework.dart:1924:7) #57 SingleChildRenderObjectElement.visitChildren (package:flutter/src/widgets/framework.dart:6271:14) #58 _InactiveElements._unmount (package:flutter/src/widgets/framework.dart:1922:13) #59 _InactiveElements._unmount. (package:flutter/src/widgets/framework.dart:1924:7) #60 ComponentElement.visitChildren (package:flutter/src/widgets/framework.dart:4807:14) #61 _InactiveElements._unmount (package:flutter/src/widgets/framework.dart:1922:13) #62 _InactiveElements._unmount. (package:flutter/src/widgets/framework.dart:1924:7) #63 ComponentElement.visitChildren (package:flutter/src/widgets/framework.dart:4807:14) #64 _InactiveElements._unmount (package:flutter/src/widgets/framework.dart:1922:13) #65 _InactiveElements._unmount. (package:flutter/src/widgets/framework.dart:1924:7) #66 ComponentElement.visitChildren (package:flutter/src/widgets/framework.dart:4807:14) #67 _InactiveElements._unmount (package:flutter/src/widgets/framework.dart:1922:13) #68 ListIterable.forEach (dart:_internal/iterable.dart:39:13) #69 _InactiveElements._unmountAll (package:flutter/src/widgets/framework.dart:1935:25) #70 BuildOwner.lockState (package:flutter/src/widgets/framework.dart:2519:15) #71 BuildOwner.finalizeTree (package:flutter/src/widgets/framework.dart:2932:7) #72 WidgetsBinding.drawFrame (package:flutter/src/widgets/binding.dart:884:19) #73 RendererBinding._handlePersistentFrameCallback (package:flutter/src/rendering/binding.dart:363:5) #74 SchedulerBinding._invokeFrameCallback (package:flutter/src/scheduler/binding.dart:1144:15) #75 SchedulerBinding.handleDrawFrame (package:flutter/src/scheduler/binding.dart:1081:9) #76 SchedulerBinding._handleDrawFrame (package:flutter/src/scheduler/binding.dart:995:5) #80 _invoke (dart:ui/hooks.dart:151:10) #81 PlatformDispatcher._drawFrame (dart:ui/platform_dispatcher.dart:308:5) #82 _drawFrame (dart:ui/hooks.dart:115:31) (elided 3 frames from dart:async)

======== Exception caught by widgets library ======================================================= The following assertion was thrown while finalizing the widget tree: A OverlayEntry was used after being disposed.

Once you have called dispose() on a OverlayEntry, it can no longer be used. When the exception was thrown, this was the stack: #0 ChangeNotifier._debugAssertNotDisposed. (package:flutter/src/foundation/change_notifier.dart:114:9) #1 ChangeNotifier._debugAssertNotDisposed (package:flutter/src/foundation/change_notifier.dart:120:6) #2 ChangeNotifier.notifyListeners (package:flutter/src/foundation/change_notifier.dart:288:12) #3 OverlayEntry._updateMounted (package:flutter/src/widgets/overlay.dart:130:5) #4 _OverlayEntryWidgetState.dispose (package:flutter/src/widgets/overlay.dart:200:18) #5 StatefulElement.unmount (package:flutter/src/widgets/framework.dart:4983:11) #6 _InactiveElements._unmount (package:flutter/src/widgets/framework.dart:1926:13) #7 ListIterable.forEach (dart:_internal/iterable.dart:39:13) #8 _InactiveElements._unmountAll (package:flutter/src/widgets/framework.dart:1935:25) #9 BuildOwner.lockState (package:flutter/src/widgets/framework.dart:2519:15) #10 BuildOwner.finalizeTree (package:flutter/src/widgets/framework.dart:2932:7) #11 WidgetsBinding.drawFrame (package:flutter/src/widgets/binding.dart:884:19) #12 RendererBinding._handlePersistentFrameCallback (package:flutter/src/rendering/binding.dart:363:5) #13 SchedulerBinding._invokeFrameCallback (package:flutter/src/scheduler/binding.dart:1144:15) #14 SchedulerBinding.handleDrawFrame (package:flutter/src/scheduler/binding.dart:1081:9) #15 SchedulerBinding._handleDrawFrame (package:flutter/src/scheduler/binding.dart:995:5) #19 _invoke (dart:ui/hooks.dart:151:10) #20 PlatformDispatcher._drawFrame (dart:ui/platform_dispatcher.dart:308:5) #21 _drawFrame (dart:ui/hooks.dart:115:31) (elided 3 frames from dart:async)

Error found in dropdown_overlay.dart file, line 159

Error: The method 'disallowIndicator' isn't defined for the class 'OverscrollIndicatorNotification'.
Try correcting the name to the name of an existing method, or defining a method named 'disallowIndicator'.notification.disallowIndicator();

Solution: I believe replacing the disallowIndicator() with disallowGlow() solves the problem!

: Warning: Operand of null-aware operation '?.' has type 'WidgetsBinding' which excludes null.

• 'WidgetsBinding' is from 'package:flutter/src/widgets/binding.dart' ('../../flutter/packages/flutter/lib/src/widgets/binding.dart'). WidgetsBinding.instance?.addPostFrameCallback((_) {

resultWidget function is added which take BuildContext and String (result) as argument so that the result can be customized. since it's not required parameter, a default widget is provided

TODO: headerWidget function

/C:/flutter/.pub-cache/hosted/pub.dartlang.org/animated_custom_dropdown-1.2.2/lib/dropdown_overlay.dart:57:29: Error: Method 'addPostFrameCallback' cannot be called on 'WidgetsBinding?' because it is potentially null.

• 'WidgetsBinding' is from 'package:flutter/src/widgets/binding.dart' ('/C:/flutter/packages/flutter/lib/src/widgets/binding.dart'). Try calling using ?. instead. WidgetsBinding.instance.addPostFrameCallback(() { ^^^^^^^^^^^^^^^^^^^^ /C:/flutter/.pub-cache/hosted/pub.dartlang.org/animated_custom_dropdown-1.2.2/lib/dropdown_overlay.dart:185:33: Error: No named parameter with the name
  'thumbVisibility'. thumbVisibility: MaterialStateProperty.all( ^^^^^^^^^^^^^^^ /C:/flutter/packages/flutter/lib/src/material/scrollbar_theme.dart:33:9: Context: Found this candidate, but the arguments don't match. const ScrollbarThemeData({ ^^^^^^^^^^^^^^^^^^ /C:/flutter/.pub-cache/hosted/pub.dartlang.org/animated_custom_dropdown-1.2.2/lib/dropdown_overlay.dart:57:5: Warning: The class 'WidgetsBinding' cannot be Try replacing '?.' with '.' WidgetsBinding?.instance.addPostFrameCallback(() { ^^^^^^^^^^^^^^ /C:/flutter/.pub-cache/hosted/pub.dartlang.org/animated_custom_dropdown-1.2.2/lib/dropdown_overlay.dart:57:30: Error: Method 'addPostFrameCallback' cannot be called on 'WidgetsBinding?' because it is potentially null.
• 'WidgetsBinding' is from 'package:flutter/src/widgets/binding.dart' ('/C:/flutter/packages/flutter/lib/src/widgets/binding.dart'). Try calling using ?. instead. WidgetsBinding?.instance.addPostFrameCallback((_) { ^^^^^^^^^^^^^^^^^^^^ /C:/flutter/.pub-cache/hosted/pub.dartlang.org/animated_custom_dropdown-1.2.2/lib/dropdown_overlay.dart:185:33: Error: No named parameter with the name
  'thumbVisibility'. thumbVisibility: MaterialStateProperty.all( ^^^^^^^^^^^^^^^ /C:/flutter/packages/flutter/lib/src/material/scrollbar_theme.dart:33:9: Context: Found this candidate, but the arguments don't match. const ScrollbarThemeData({ ^^^^^^^^^^^^^^^^^^

I tried to override mouse cursor by using MouseRegion( cursor: SystemMouseCursors.click, child: CustomDropdown.search()... ) to click for web development but was unsuccessful. Is it possible to change this so that we can edit pointer to click when use hovers dropdown while using browser ?