diff --git a/src/Framework/Framework/Controls/ModalDialog.cs b/src/Framework/Framework/Controls/ModalDialog.cs
new file mode 100644
index 0000000000..c1bbf9d1c7
--- /dev/null
+++ b/src/Framework/Framework/Controls/ModalDialog.cs
@@ -0,0 +1,82 @@
+using System;
+using System.Net;
+using System.Text;
+using DotVVM.Framework.Binding;
+using DotVVM.Framework.Binding.Expressions;
+using DotVVM.Framework.Hosting;
+using DotVVM.Framework.ResourceManagement;
+using Newtonsoft.Json;
+
+namespace DotVVM.Framework.Controls
+{
+    /// <summary>
+    /// Renders a HTML native dialog element, it is opened using the showModal function when the <see cref="Open" /> property is set to true
+    /// </summary>
+    /// <remarks>
+    /// * Non-modal dialogs may be simply binding the attribute of the HTML dialog element
+    /// * The dialog may be closed by button with formmethod="dialog", when ESC is pressed, or when the backdrop is clicked if <see cref="CloseOnBackdropClick" /> = true
+    /// </remarks>
+    [ControlMarkupOptions()]
+    public class ModalDialog : HtmlGenericControl
+    {
+        public ModalDialog()
+            : base("dialog", false)
+        {
+        }
+
+        /// <summary> A value indicating whether the dialog is open. The value can either be a boolean or an object (not false or not null -> shown). On close, the value is written back into the Open binding. </summary>
+        [MarkupOptions(AllowHardCodedValue = false)]
+        public object? Open
+        {
+            get { return GetValue(OpenProperty); }
+            set { SetValue(OpenProperty, value); }
+        }
+        public static readonly DotvvmProperty OpenProperty =
+            DotvvmProperty.Register<object, ModalDialog>(nameof(Open), null);
+
+        /// <summary> Add an event handler which closes the dialog when the backdrop is clicked. </summary>
+        public bool CloseOnBackdropClick
+        {
+            get { return (bool?)GetValue(CloseOnBackdropClickProperty) ?? false; }
+            set { SetValue(CloseOnBackdropClickProperty, value); }
+        }
+        public static readonly DotvvmProperty CloseOnBackdropClickProperty =
+            DotvvmProperty.Register<bool, ModalDialog>(nameof(CloseOnBackdropClick), false);
+
+        /// <summary> Triggered when the dialog is closed. Called only if it was closed by user input, not by <see cref="Open"/> change. </summary>
+        public Command? Close
+        {
+            get { return (Command?)GetValue(CloseProperty); }
+            set { SetValue(CloseProperty, value); }
+        }
+        public static readonly DotvvmProperty CloseProperty =
+            DotvvmProperty.Register<Command, ModalDialog>(nameof(Close));
+
+        protected override void AddAttributesToRender(IHtmlWriter writer, IDotvvmRequestContext context)
+        {
+            var valueBinding = GetValueBinding(OpenProperty);
+            if (valueBinding is {})
+            {
+                writer.AddKnockoutDataBind("dotvvm-modal-open", this, valueBinding);
+            }
+            else if (!(Open is false or null))
+            {
+                // we have to use the binding handler instead of `open` attribute, because we need to call the showModal function
+                writer.AddKnockoutDataBind("dotvvm-modal-open", "true");
+            }
+
+            if (GetValueOrBinding<bool>(CloseOnBackdropClickProperty) is {} x && !x.ValueEquals(false))
+            {
+                writer.AddKnockoutDataBind("dotvvm-modal-backdrop-close", x.GetJsExpression(this));
+            }
+
+            if (GetCommandBinding(CloseProperty) is {} close)
+            {
+                var postbackScript = KnockoutHelper.GenerateClientPostBackScript(nameof(Close), close, this, returnValue: null);
+                writer.AddAttribute("onclose", "if (event.target.returnValue!=\"_dotvvm_modal_supress_onclose\") {" + postbackScript + "}");
+            }
+
+            base.AddAttributesToRender(writer, context);
+        }
+    }
+}
diff --git a/src/Framework/Framework/Resources/Scripts/binding-handlers/all-handlers.ts b/src/Framework/Framework/Resources/Scripts/binding-handlers/all-handlers.ts
index ccacf44549..6480b3a0a2 100644
--- a/src/Framework/Framework/Resources/Scripts/binding-handlers/all-handlers.ts
+++ b/src/Framework/Framework/Resources/Scripts/binding-handlers/all-handlers.ts
@@ -10,6 +10,7 @@ import gridviewdataset from './gridviewdataset'
 import namedCommand from './named-command'
 import fileUpload from './file-upload'
 import jsComponents from './js-component'
+import modalDialog from './modal-dialog'
 
 type KnockoutHandlerDictionary = {
     [name: string]: KnockoutBindingHandler
@@ -26,7 +27,8 @@ const allHandlers: KnockoutHandlerDictionary = {
     ...gridviewdataset,
     ...namedCommand,
     ...fileUpload,
-    ...jsComponents
+    ...jsComponents,
+    ...modalDialog
 }
 
 export default allHandlers
diff --git a/src/Framework/Framework/Resources/Scripts/binding-handlers/modal-dialog.ts b/src/Framework/Framework/Resources/Scripts/binding-handlers/modal-dialog.ts
new file mode 100644
index 0000000000..9d25f3a0c1
--- /dev/null
+++ b/src/Framework/Framework/Resources/Scripts/binding-handlers/modal-dialog.ts
@@ -0,0 +1,42 @@
+export default {
+    "dotvvm-modal-open": {
+        init(element: HTMLDialogElement, valueAccessor: () => any) {
+            element.addEventListener("close", () => {
+                const value = valueAccessor();
+                if (ko.isWriteableObservable(value)) {
+                    // if the value is object, set it to null
+                    value(typeof value.peek() == "boolean" ? false : null)
+                }
+            })
+        },
+        update(element: HTMLDialogElement, valueAccessor: () => any) {
+            const value = ko.unwrap(valueAccessor()),
+                  shouldOpen = value != null && value !== false;
+            if (shouldOpen != element.open) {
+                if (shouldOpen) {
+                    element.returnValue = "" // reset returnValue, ESC key leaves the old return value
+                    element.showModal()
+                } else {
+                    element.close("_dotvvm_modal_supress_onclose")
+                }
+            }
+        },
+    },
+    "dotvvm-modal-backdrop-close": {
+        init(element: HTMLDialogElement, valueAccessor: () => any) {
+            // closes the dialog when the backdrop is clicked
+            element.addEventListener("click", (e) => {
+                if (e.target == element) {
+                    const elementRect = element.getBoundingClientRect(),
+                          x = e.clientX,
+                          y = e.clientY;
+                    if (x < elementRect.left || x > elementRect.right || y < elementRect.top || y > elementRect.bottom) {
+                        if (ko.unwrap(valueAccessor())) {
+                            element.close();
+                        }
+                    }
+                }
+            })
+        }
+    }
+}
diff --git a/src/Samples/Common/ViewModels/FeatureSamples/ModalDialog/ModalDialogViewModel.cs b/src/Samples/Common/ViewModels/FeatureSamples/ModalDialog/ModalDialogViewModel.cs
new file mode 100644
index 0000000000..f0181260aa
--- /dev/null
+++ b/src/Samples/Common/ViewModels/FeatureSamples/ModalDialog/ModalDialogViewModel.cs
@@ -0,0 +1,42 @@
+
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Linq.Expressions;
+using System.Net.Http.Headers;
+using System.Text;
+using DotVVM.Framework.ViewModel;
+
+namespace DotVVM.Samples.Common.ViewModels.FeatureSamples.ModalDialog
+{
+    public class ModalDialogViewModel : DotvvmViewModelBase
+    {
+        public bool Dialog1Shown { get; set; }
+        public bool DialogChained1Shown { get; set; }
+        public bool DialogChained2Shown { get; set; }
+        public bool CloseEventDialogShown { get; set; }
+
+        public int? NullableIntController { get; set; }
+        public string NullableStringController { get; set; }
+
+        public DialogModel DialogWithModel { get; set; } = null;
+
+        public int CloseEventCounter { get; set; } = 0;
+
+        public void ShowDialogWithModel()
+        {
+            DialogWithModel = new DialogModel() { Property = "Hello" };
+        }
+
+        public void CloseDialogWithEvent()
+        {
+            CloseEventDialogShown = false;
+        }
+
+        public class DialogModel
+        {
+            public string Property { get; set; }
+        }
+    }
+
+}
diff --git a/src/Samples/Common/Views/FeatureSamples/ModalDialog/ModalDialog.dothtml b/src/Samples/Common/Views/FeatureSamples/ModalDialog/ModalDialog.dothtml
new file mode 100644
index 0000000000..ac0188eb3a
--- /dev/null
+++ b/src/Samples/Common/Views/FeatureSamples/ModalDialog/ModalDialog.dothtml
@@ -0,0 +1,79 @@
+@viewModel DotVVM.Samples.Common.ViewModels.FeatureSamples.ModalDialog.ModalDialogViewModel
+
+<!DOCTYPE html>
+<html lang="en">
+<head>
+    <meta charset="utf-8" />
+    <title></title>
+
+    <style>
+        .button-active {
+            background-color: #4CAF50;
+        }
+    </style>
+</head>
+<body>
+    <h1>Modal dialogs</h1>
+    
+    <p>
+        <dot:Button data-ui="btn-open-simple" Text="Simple dialog" Click="{staticCommand: Dialog1Shown = true}" Class-button-active={value: Dialog1Shown} />
+        <dot:Button data-ui="btn-open-chained1" Text="Chained dialog" Click="{staticCommand: DialogChained1Shown = true}" Class-button-active={value: DialogChained1Shown} />
+        <dot:Button data-ui="btn-open-close-event" Text="Dialog with clickable backdrop and close event" Click="{staticCommand: CloseEventDialogShown = true}" Class-button-active={value: CloseEventDialogShown} />
+        <dot:Button data-ui="btn-open-view-model" Text="Dialog with view model" Click="{command: ShowDialogWithModel()}" Class-button-active={value: DialogWithModel != null} />
+        <dot:Button data-ui="btn-open-int" Text="Dialog controlled by nullable number" Click="{command: NullableIntController = 0}" Class-button-active={value: NullableIntController != null} />
+        <dot:Button data-ui="btn-open-string" Text="Dialog controlled by nullable string" Click="{staticCommand: NullableStringController = ""}" Class-button-active={value: NullableStringController != null} />
+    </p>
+    <p>
+        Close events: <span data-ui="close-event-counter" InnerText={value: CloseEventCounter} />
+    </p>
+
+    <dot:ModalDialog Open={value: Dialog1Shown} data-ui=simple>
+        <form>
+            This is a simple modal dialog, close it by pressing ESC or clicking the <button data-ui=btn-close formmethod="dialog" type="submit">Form method=dialog</button> button.
+        </form>
+    </dot:ModalDialog>
+
+    <dot:ModalDialog Open={value: DialogChained1Shown} data-ui=chained1>
+        <p>This is the first chained modal dialog.</p>
+        <form>
+            <dot:Button data-ui=btn-next Text="Next" Click={staticCommand: DialogChained1Shown = false; DialogChained2Shown = true} />
+            <button data-ui=btn-close formmethod="dialog" type="submit">Cancel</button>
+        </form>
+    </dot:ModalDialog>
+
+    <dot:ModalDialog Open={value: DialogChained2Shown} data-ui=chained2>
+        <p>This is the second chained modal dialog.</p>
+        <dot:Button data-ui=btn-close Text="Close" Click={staticCommand: DialogChained2Shown = false} />
+    </dot:ModalDialog>
+
+    <dot:ModalDialog Open={value: CloseEventDialogShown} CloseOnBackdropClick Close={staticCommand: CloseEventCounter = CloseEventCounter + 1} data-ui=close-event>
+        Closing the dialog will increase the counter. Either
+        <ul>
+            <li>Click the backdrop</li>
+            <li>Press ESC</li>
+            <li><dot:Button data-ui=btn-close-staticcommand Click={staticCommand: CloseEventDialogShown=false}>Use staticCommand</dot:Button></li>
+            <li><dot:Button data-ui=btn-close-command Click={command: CloseDialogWithEvent()}>Use command</dot:Button></li>
+            <li> <form method="dialog"><button data-ui=btn-close-form type="submit">Form method=dialog</button></form></li>
+        </ul>
+    </dot:ModalDialog>
+
+    <dot:ModalDialog Open={value: DialogWithModel} data-ui=view-model>
+        <p>Edit this field: <dot:TextBox Text={value: DialogWithModel.Property} /> </p>
+        <p>
+            <dot:Button data-ui=btn-save Text="Save" Click={command: DialogWithModel = null} />
+            <form method="dialog"><button data-ui=btn-close type="submit">Cancel</button></form>
+        </p>
+    </dot:ModalDialog>
+
+    <dot:ModalDialog Open={value: NullableIntController} data-ui=int>
+        the number: <dot:TextBox data-ui=editor Text={value: NullableIntController} />
+        <form method="dialog"><button data-ui=btn-close type="submit">Close</button></form>
+    </dot:ModalDialog>
+
+    <dot:ModalDialog Open={value: NullableStringController} data-ui=string>
+        the string: <dot:TextBox data-ui=editor Text={value: NullableStringController} />
+        <form method="dialog"><button data-ui=btn-close type="submit">Close</button></form>
+    </dot:ModalDialog>
+</body>
+</html>
+
diff --git a/src/Samples/Tests/Abstractions/SamplesRouteUrls.designer.cs b/src/Samples/Tests/Abstractions/SamplesRouteUrls.designer.cs
index b7a57dbe57..6b287d9ae9 100644
--- a/src/Samples/Tests/Abstractions/SamplesRouteUrls.designer.cs
+++ b/src/Samples/Tests/Abstractions/SamplesRouteUrls.designer.cs
@@ -297,6 +297,7 @@ public partial class SamplesRouteUrls
         public const string FeatureSamples_MarkupControl_ResourceBindingInControlProperty = "FeatureSamples/MarkupControl/ResourceBindingInControlProperty";
         public const string FeatureSamples_MarkupControl_StaticCommandInMarkupControl = "FeatureSamples/MarkupControl/StaticCommandInMarkupControl";
         public const string FeatureSamples_MarkupControl_StaticCommandInMarkupControlCallingRegularCommand = "FeatureSamples/MarkupControl/StaticCommandInMarkupControlCallingRegularCommand";
+        public const string FeatureSamples_ModalDialog_ModalDialog = "FeatureSamples/ModalDialog/ModalDialog";
         public const string FeatureSamples_NestedMasterPages_Content = "FeatureSamples/NestedMasterPages/Content";
         public const string FeatureSamples_NoJsForm_NoJsForm = "FeatureSamples/NoJsForm/NoJsForm";
         public const string FeatureSamples_ParameterBinding_OptionalParameterBinding = "FeatureSamples/ParameterBinding/OptionalParameterBinding";
diff --git a/src/Samples/Tests/Tests/Feature/CompilationPageTests.cs b/src/Samples/Tests/Tests/Feature/CompilationPageTests.cs
index a408d3b97e..e5823f40a3 100644
--- a/src/Samples/Tests/Tests/Feature/CompilationPageTests.cs
+++ b/src/Samples/Tests/Tests/Feature/CompilationPageTests.cs
@@ -19,15 +19,18 @@ public void Feature_CompilationPage_SmokeTest()
         {
             RunInAllBrowsers(browser => {
                 browser.NavigateToUrl("/_dotvvm/diagnostics/compilation");
-                browser.Single("compile-all-button", By.Id).Click();
+                browser.WaitFor(() => { browser.Single("compile-all-button", By.Id).Click(); }, timeout: 15_000);
                 browser.Single("Routes", SelectByButtonText).Click();
 
                 // shows failed pages
-                Assert.InRange(browser.FindElements("tbody tr.success").Count, 10, int.MaxValue);
-                Assert.InRange(browser.FindElements("tbody tr.failure").Count, 10, int.MaxValue);
                 browser.WaitFor(() => {
-                    AssertUI.HasClass(TableRow(browser, "FeatureSamples_CompilationPage_BindingsTestError"), "failure", waitForOptions: WaitForOptions.Disabled);
-                }, timeout: 10_000);
+                    Assert.InRange(browser.FindElements("tbody tr.success").Count, 10, int.MaxValue);
+                    Assert.InRange(browser.FindElements("tbody tr.failure").Count, 10, int.MaxValue);
+                    var failedRow = () => TableRow(browser, "FeatureSamples_CompilationPage_BindingsTestError");
+                    AssertUI.InnerTextEquals(failedRow().ElementAt("td", 1), "FeatureSamples/CompilationPage/BindingsTestError");
+                    AssertUI.InnerTextEquals(failedRow().ElementAt("td", 3), "CompilationFailed");
+                    AssertUI.HasClass(failedRow(), "failure", waitForOptions: WaitForOptions.Disabled);
+                }, timeout: 60_000);
                 AssertUI.HasNotClass(TableRow(browser, "FeatureSamples_CompilationPage_BindingsTest"), "failure");
 
                 // shows some errors and warnings
diff --git a/src/Samples/Tests/Tests/Feature/ModalDialogTests.cs b/src/Samples/Tests/Tests/Feature/ModalDialogTests.cs
new file mode 100644
index 0000000000..5984d245ea
--- /dev/null
+++ b/src/Samples/Tests/Tests/Feature/ModalDialogTests.cs
@@ -0,0 +1,115 @@
+using System;
+using System.Linq;
+using DotVVM.Samples.Tests.Base;
+using DotVVM.Testing.Abstractions;
+using OpenQA.Selenium;
+using OpenQA.Selenium.Interactions;
+using Riganti.Selenium.Core;
+using Riganti.Selenium.Core.Abstractions;
+using Riganti.Selenium.Core.Api;
+using Riganti.Selenium.DotVVM;
+using Xunit;
+
+namespace DotVVM.Samples.Tests.Feature
+{
+    public class ModalDialogTests : AppSeleniumTest
+    {
+        public ModalDialogTests(Xunit.Abstractions.ITestOutputHelper output) : base(output)
+        {
+        }
+
+        IElementWrapper OpenDialog(IBrowserWrapper browser, string dialogId)
+        {
+            var button = browser.Single($"btn-open-{dialogId}", SelectByDataUi);
+            AssertUI.IsNotDisplayed(browser.Single(dialogId, SelectByDataUi));
+            button.Click();
+            AssertUI.HasClass(browser.Single($"btn-open-{dialogId}", SelectByDataUi), "button-active");
+            var dialog = browser.Single(dialogId, SelectByDataUi);
+            AssertUI.IsDisplayed(dialog);
+            return dialog;
+        }
+
+        void CheckDialogCloses(IBrowserWrapper browser, string id, Action<IElementWrapper> closeAction)
+        {
+            var dialog = OpenDialog(browser, id);
+            closeAction(dialog);
+            AssertUI.IsNotDisplayed(browser.Single(id, SelectByDataUi));
+            AssertUI.HasNotClass(browser.Single($"btn-open-{id}", SelectByDataUi), "button-active");
+        }
+
+        [Fact]
+        public void Feature_ModalDialog_Simple()
+        {
+            RunInAllBrowsers(browser => {
+                browser.NavigateToUrl(SamplesRouteUrls.FeatureSamples_ModalDialog_ModalDialog);
+                CheckDialogCloses(browser, "simple", dialog => dialog.Single("btn-close", SelectByDataUi).Click());
+                CheckDialogCloses(browser, "simple", dialog => {
+                    // backdrop click does nothing
+                    new Actions(browser.Driver).MoveToLocation(1, 1).Click().Perform();
+                    AssertUI.IsDisplayed(dialog);
+
+                    dialog.SendKeys(Keys.Escape);
+                    AssertUI.IsNotDisplayed(dialog);
+                });
+
+            });
+        }
+
+        [Fact]
+        public void Feature_ModalDialog_Chained()
+        {
+            RunInAllBrowsers(browser => {
+                browser.NavigateToUrl(SamplesRouteUrls.FeatureSamples_ModalDialog_ModalDialog);
+                var dialog1 = OpenDialog(browser, "chained1");
+                dialog1.Single("btn-next", SelectByDataUi).Click();
+                AssertUI.IsNotDisplayed(dialog1);
+                var dialog2 = browser.Single("chained2", SelectByDataUi);
+                AssertUI.IsDisplayed(dialog2);
+                dialog2.Single("btn-close", SelectByDataUi).Click();
+                AssertUI.IsNotDisplayed(dialog2);
+            });
+        }
+
+        [Fact]
+        public void Feature_ModalDialog_CloseEvent()
+        {
+            RunInAllBrowsers(browser => {
+                browser.NavigateToUrl(SamplesRouteUrls.FeatureSamples_ModalDialog_ModalDialog);
+
+                CheckDialogCloses(browser, "close-event", dialog => dialog.Single("btn-close-staticcommand", SelectByDataUi).Click());
+                AssertUI.InnerTextEquals(browser.Single("close-event-counter", SelectByDataUi), "0");
+                CheckDialogCloses(browser, "close-event", dialog => dialog.Single("btn-close-command", SelectByDataUi).Click());
+                AssertUI.InnerTextEquals(browser.Single("close-event-counter", SelectByDataUi), "0");
+                CheckDialogCloses(browser, "close-event", dialog => dialog.Single("btn-close-form", SelectByDataUi).Click());
+                AssertUI.InnerTextEquals(browser.Single("close-event-counter", SelectByDataUi), "1");
+                CheckDialogCloses(browser, "close-event", dialog => dialog.SendKeys(Keys.Escape));
+                AssertUI.InnerTextEquals(browser.Single("close-event-counter", SelectByDataUi), "2");
+
+                CheckDialogCloses(browser, "close-event", dialog => {
+                    // dialog click
+                    this.TestOutput.WriteLine($"Dialog location: {dialog.WebElement.Location}");
+                    new Actions(browser.Driver).MoveToLocation(dialog.WebElement.Location.X + 10, dialog.WebElement.Location.Y + 10).Click().Perform();
+                    AssertUI.IsDisplayed(dialog);
+                    // backdrop click
+                    new Actions(browser.Driver).MoveToLocation(1, 1).Click().Perform();
+
+                });
+                AssertUI.InnerTextEquals(browser.Single("close-event-counter", SelectByDataUi), "3");
+            });
+        }
+
+        [Fact]
+        public void Feature_ModalDialog_ModelController()
+        {
+            RunInAllBrowsers(browser => {
+                browser.NavigateToUrl(SamplesRouteUrls.FeatureSamples_ModalDialog_ModalDialog);
+                CheckDialogCloses(browser, "view-model", dialog => dialog.Single("btn-save", SelectByDataUi).Click());
+                CheckDialogCloses(browser, "view-model", dialog => dialog.Single("btn-close", SelectByDataUi).Click());
+                CheckDialogCloses(browser, "int", dialog => dialog.Single("btn-close", SelectByDataUi).Click());
+                // clearing the numeric input puts null into the nullable integer controller
+                CheckDialogCloses(browser, "int", dialog => dialog.Single("editor", SelectByDataUi).Clear());
+                CheckDialogCloses(browser, "string", dialog => dialog.Single("btn-close", SelectByDataUi).Click());
+            });
+        }
+    }
+}
diff --git a/src/Samples/Tests/Tests/Feature/PostbackConcurrencyTests.cs b/src/Samples/Tests/Tests/Feature/PostbackConcurrencyTests.cs
index 16a7a559a5..d7f2d84662 100644
--- a/src/Samples/Tests/Tests/Feature/PostbackConcurrencyTests.cs
+++ b/src/Samples/Tests/Tests/Feature/PostbackConcurrencyTests.cs
@@ -156,16 +156,17 @@ public void Feature_PostbackConcurrency_StressTest_Default()
 
                 browser.ElementAt("input[type=button]", 1).Click();
 
-                Thread.Sleep(10000);
-                var before = int.Parse(browser.Single(".result-before").GetInnerText().Trim());
-                var rejected = int.Parse(browser.Single(".result-rejected").GetInnerText().Trim());
-                var after = int.Parse(browser.Single(".result-after").GetInnerText().Trim());
-                var value = int.Parse(browser.Single(".result-value").GetInnerText().Trim());
-
-                Assert.True(0 < value && value <= 100);
-                Assert.Equal(100, before);
-                Assert.Equal(100, after);
-                Assert.Equal(0, rejected);
+                browser.WaitFor(() => {
+                    var before = int.Parse(browser.Single(".result-before").GetInnerText().Trim());
+                    var rejected = int.Parse(browser.Single(".result-rejected").GetInnerText().Trim());
+                    var after = int.Parse(browser.Single(".result-after").GetInnerText().Trim());
+                    var value = int.Parse(browser.Single(".result-value").GetInnerText().Trim());
+
+                    Assert.InRange(value, 1, 100);
+                    Assert.Equal(100, before);
+                    Assert.Equal(100, after);
+                    Assert.Equal(0, rejected);
+                }, timeout: 30_000);
             });
         }
 
@@ -178,15 +179,16 @@ public void Feature_PostbackConcurrency_StressTest_Deny()
 
                 browser.ElementAt("input[type=button]", 3).Click();
 
-                Thread.Sleep(10000);
-                var before = int.Parse(browser.Single(".result-before").GetInnerText().Trim());
-                var rejected = int.Parse(browser.Single(".result-rejected").GetInnerText().Trim());
-                var after = int.Parse(browser.Single(".result-after").GetInnerText().Trim());
-                var value = int.Parse(browser.Single(".result-value").GetInnerText().Trim());
-
-                Assert.True(0 < value && value <= 100);
-                Assert.Equal(100, before + rejected);
-                Assert.Equal(100, after);
+                browser.WaitFor(() => {
+                    var before = int.Parse(browser.Single(".result-before").GetInnerText().Trim());
+                    var rejected = int.Parse(browser.Single(".result-rejected").GetInnerText().Trim());
+                    var after = int.Parse(browser.Single(".result-after").GetInnerText().Trim());
+                    var value = int.Parse(browser.Single(".result-value").GetInnerText().Trim());
+
+                    Assert.InRange(value, 1, 100);
+                    Assert.Equal(100, before + rejected);
+                    Assert.Equal(100, after);
+                }, timeout: 30_000);
             });
         }
 
@@ -199,16 +201,17 @@ public void Feature_PostbackConcurrency_StressTest_Queue()
 
                 browser.ElementAt("input[type=button]", 5).Click();
 
-                Thread.Sleep(10000);
-                var before = int.Parse(browser.Single(".result-before").GetInnerText().Trim());
-                var rejected = int.Parse(browser.Single(".result-rejected").GetInnerText().Trim());
-                var after = int.Parse(browser.Single(".result-after").GetInnerText().Trim());
-                var value = int.Parse(browser.Single(".result-value").GetInnerText().Trim());
-
-                Assert.Equal(100, value);
-                Assert.Equal(100, before);
-                Assert.Equal(100, after);
-                Assert.Equal(0, rejected);
+                browser.WaitFor(() => {
+                    var before = int.Parse(browser.Single(".result-before").GetInnerText().Trim());
+                    var rejected = int.Parse(browser.Single(".result-rejected").GetInnerText().Trim());
+                    var after = int.Parse(browser.Single(".result-after").GetInnerText().Trim());
+                    var value = int.Parse(browser.Single(".result-value").GetInnerText().Trim());
+
+                    Assert.Equal(100, value);
+                    Assert.Equal(100, before);
+                    Assert.Equal(100, after);
+                    Assert.Equal(0, rejected);
+                }, timeout: 30_000);
             });
         }
 
diff --git a/src/Tests/Runtime/config-tests/ConfigurationSerializationTests.SerializeDefaultConfig.json b/src/Tests/Runtime/config-tests/ConfigurationSerializationTests.SerializeDefaultConfig.json
index 17991ed4b6..4f5cde2cf5 100644
--- a/src/Tests/Runtime/config-tests/ConfigurationSerializationTests.SerializeDefaultConfig.json
+++ b/src/Tests/Runtime/config-tests/ConfigurationSerializationTests.SerializeDefaultConfig.json
@@ -1177,6 +1177,20 @@
         "defaultValue": ""
       }
     },
+    "DotVVM.Framework.Controls.ModalDialog": {
+      "Close": {
+        "type": "DotVVM.Framework.Binding.Expressions.Command, DotVVM.Framework",
+        "isCommand": true
+      },
+      "CloseOnBackdropClick": {
+        "type": "System.Boolean",
+        "defaultValue": false
+      },
+      "Open": {
+        "type": "System.Object",
+        "onlyBindings": true
+      }
+    },
     "DotVVM.Framework.Controls.MultiSelector": {
       "SelectedValues": {
         "type": "System.Object",
@@ -2216,6 +2230,10 @@
       "baseType": "DotVVM.Framework.Controls.HtmlGenericControl, DotVVM.Framework",
       "withoutContent": true
     },
+    "DotVVM.Framework.Controls.ModalDialog": {
+      "assembly": "DotVVM.Framework",
+      "baseType": "DotVVM.Framework.Controls.HtmlGenericControl, DotVVM.Framework"
+    },
     "DotVVM.Framework.Controls.MultiSelect": {
       "assembly": "DotVVM.Framework",
       "baseType": "DotVVM.Framework.Controls.MultiSelectHtmlControlBase, DotVVM.Framework"