test for removing GetX dialogs with removeRoute + extension methods.

control_dialogs_demo.dart

/// Copyright roipeker 2020.

// Web Sample:
// https://roi-getx-kill-dialog.surge.sh/

import 'package:flutter/material.dart';
import 'package:get/get.dart';

/// proof of concept
/// execute in main.dart:
/// main() => OverlayDemo.main();

class OverlayDemo {
  static void main() {
    Get.put(MyController());
    runApp(
      GetMaterialApp(
        debugShowCheckedModeBanner: false,
        home: _OverlayDemo(),
      ),
    );
  }
}

class MyDialog extends StatelessWidget {
  final int id;
  final int total;

  MyDialog({
    this.id,
    this.total,
  });

  @override
  Widget build(BuildContext context) {
    context.addRouteKey(id);
    return Padding(
      padding: EdgeInsets.only(top: 64.0 * id),
      child: Dialog(
        backgroundColor: Colors.redAccent,
        elevation: 2,
        child: Column(
          mainAxisSize: MainAxisSize.min,
          children: [
            Text(
              'Dialog $id',
              style: Get.textTheme.headline4,
            ),
            ...List.generate(total, _button),
          ],
        ),
      ),
    );
  }

  MyController get myController => Get.find();

  void _killRoute(int routeId) {
    final removed = Get.killRoute(routeId);
    if (removed) {
      myController.removedRouteId(routeId);
    }
  }

  Widget _button(int routeId) {
    return Obx(
      () {
        final exists = myController.routeExists(routeId);
        final textStyle =
            !exists ? TextStyle(decoration: TextDecoration.lineThrough) : null;
        return FlatButton(
          onPressed: exists ? () => _killRoute(routeId) : null,
          child: Text(
            'dialog $routeId',
            style: textStyle,
          ),
        );
      },
    );
  }
}

class MyController extends GetxController {
  final reactiveList = <bool>[].obs;

  @override
  void onReady() {
    print(';ready');
  }

  Future<void> press() async {
    final numDialogs = 8;
    reactiveList.clear();
    reactiveList.addAll(List.generate(numDialogs, (index) => true));

    for (var i = 0; i < numDialogs; ++i) {
      Get.dialog(
        MyDialog(id: i, total: numDialogs),
        barrierDismissible: false,
        barrierColor: Colors.black12,
        transitionCurve: Curves.easeOutExpo,
        transitionDuration: .3.seconds,
      );
      await .35.seconds.delay();
    }

//    await .5.seconds.delay();
//    _killRoute(1);
//    await .5.seconds.delay();
//    _killRoute(4);
//    await .5.seconds.delay();
//    _killRoute(3);
  }

  void _killRoute(int i) {
    Get.killRoute(i);
    removedRouteId(i);
  }

  void removedRouteId(int routeId) {
    reactiveList[routeId] = false;
  }

  bool routeExists(int routeId) {
    return reactiveList[routeId];
  }
}

class _OverlayDemo extends GetView<MyController> {
  @override
  Widget build(BuildContext context) {
    return Scaffold(
        body: Center(
      child: FlatButton(
        onPressed: controller.press,
        child: Text('open'),
      ),
    ));
  }
}

/// EXTENSION
///
extension MyContextExt on BuildContext {
  void addRouteKey(int key) => DialogManager.add(key, ModalRoute.of(this));
}

extension MyDialogExt on GetInterface {
  void addRouteKey(int key, Route route) => DialogManager.add(key, route);

  bool killRoute(int key) => DialogManager.remove(key);
}

class DialogManager {
  static var _maps = <int, Route>{};
  static void add(int key, Route route) => _maps[key] = route;
  static bool remove(int key) {
    if (!_maps.containsKey(key)) return false;
    navigator.removeRoute(_maps[key]);
    _maps.remove(key);
    return true;
  }
}

This is another level.
Soooo cool.
This is Prefect.
This is what Looking for.
This should fix almost all dialog issues.