This issue seems fixed for AzureAD while it is not for WSFederation authentication

• https://github.com/AzureAD/azure-activedirectory-identitymodel-extensions-for-dotnet/issues/495

It seems the final solution is to manually remove the entries with null/empty key from the submitted form

It should be similar to the RadAjaxManager.GetCurrent(Page) method and return the first RadWindowManager instance on the page. Note that, unlike most other manager type controls there may be multiple RadWindowManagers on the page in a valid scenario.

You can work around this by storing the currently focused element before calling autoSize()
and then using the OnClientAutoSizeEnd event (http://www.telerik.com/help/aspnet-ajax/window-client-side-events-onclientautosizeend.html) to restore the focus.

//this goes in the content
function autoSizeWnd() {
	//code that manipulates the content so autosizing is needed
	var oWnd = getRadWindow();
	if ($telerik.isIE) { //assumes you have the Telerik core client-side libraries loaded (e.g., by having a Telerik control on this page). If you don't, you can skip the check or add them manually
		oWnd.__currActElem = document.activeElement;
	}
	oWnd.autoSize();
}


//this goes in the main page where the RadWindow is declared
function autoSizeEndHandler(sender, args) {
	setTimeout(function () {
		if (sender.__currActElem && sender.__currActElem.focus) {
			sender.__currActElem.focus();
		}
	}, 0);
}

A JavaScript error is thrown when a dialog that has animations enabled is closed if unobtrusive validation is used on the page.

Workarounds are:
- avoid animations
- OR, add the following script at the end of the form and remove it when this issue is fixed internally
Telerik.Web.UI.RadWindow.prototype._hide = function() {
	if (!this.get_animation() || this.get_animation() == 0) {
		this._afterHide();
	} else {
		if (this._enableShadow && $telerik.isIE) {
			this._setShadowCSSClass(false);
		} 
		var fnc = Function.createDelegate(this, this._afterHide),
			isMaximized = this.isMaximized(),
			duration = this.get_animationDuration();
		var popupElem = $telerik.$(this._popupElement);
		if (popupElem.length > 0 && popupElem.stopTransition) {
			$telerik.$(this._popupElement).stopTransition().transition({ opacity: 0 }, duration, "linear", function () {
				fnc(isMaximized);
			});
		} else {
			fnc(isMaximized);
		}
	}
}

When I set RadWindow property VisibleTitlebar="false" then top border is missing on window.
Here is sample code:
<telerik:RadWindow runat="server" ID="GenerateReportWaitWindow" Width="440px" Height="200px" 
                    VisibleTitlebar="false" Modal="true" ReloadOnShow="false" VisibleStatusbar="false" 
                    VisibleOnPageLoad="false" EnableShadow="false" Animation="Fade" Behaviors="None"
                    Title="Čakajte prosím...">
                    <ContentTemplate>
                        <div style="min-height: 66%;">
                            <div style="padding-top: 30px; padding-bottom: 45px; text-align: center; font-weight: bold;">
                                <asp:Label ID="Label4" runat="server">Prebieha vytváranie tlačovej zostavy. Čakajte prosím.</asp:Label>
                              
                                <asp:Label ID="Label5" runat="server">(V závislosti od počtu záznamov to môže trvať aj niekoľko minút...)</asp:Label>
                                <asp:Label ID="Label6" runat="server" ForeColor="Red" Style="display: none;"></asp:Label>
                          
                            </div>
                            <div style="margin-left: auto; margin-right: auto; text-align: center;">
                                <asp:Image ID="Image2" runat="server" ImageUrl="~/Images/Animated/loading1.gif" />
                            </div>
                        </div>
                    </ContentTemplate>
                </telerik:RadWindow>

Admin comment:
Actually there is 1px top border, but it is hard to be noticed. As a temporary solution, one can increase it via the following padding:

Copy Code
<style>
    .RadWindow {
        padding: 4px 5px 5px !important;
    }
</style>

A possible workaround is to remove the wrong skin-specific CSS class and add the correct one, for example:
<telerik:RadWindow ID="first" runat="server" Skin="Silk" Height="200px" Width="200px" VisibleOnPageLoad="true" RenderMode="Lightweight"
				   OnClientShow="applyProperSkinClass">
	<ContentTemplate>
		<asp:Label runat="server" Text="Silk"></asp:Label>
	</ContentTemplate>
</telerik:RadWindow>
<telerik:RadWindow ID="second" runat="server" Skin="MetroTouch" Height="200px" Width="200px" VisibleOnPageLoad="true" RenderMode="Lightweight"
				   OnClientShow="applyProperSkinClass">
	<ContentTemplate>
		<asp:Label runat="server" Text="MetroTouch"></asp:Label>
	</ContentTemplate>
</telerik:RadWindow>
<script type="text/javascript">
	function applyProperSkinClass(sender, args) {
		var classesArray = $telerik.$(sender.get_popupElement()).attr('class').split(' ');
		for (var i = 0; i < classesArray.length; i++) {
			if (classesArray[i].indexOf("RadWindow_") > -1) {
				$telerik.$(sender.get_popupElement()).removeClass(classesArray[i]);
			}
		}
		$telerik.$(sender.get_popupElement()).addClass("RadWindow_" + sender.get_skin());
		var wndBounds = sender.getWindowBounds();
		sender.setSize(wndBounds.width, wndBounds.height);
	}
</script>

Add role="button" to the anchor tags in RadAlert, RadConfirm, RadPrompt that generate the OK buttons and other buttons on these popups for 508 compliance.  Currently the buttons are being announced as Links (in NVDA).  Workaround is to use a line of JS/Jquery to add the role to the anchor tag.

This is related to a browser bug in accessing the document.activeElement property inside an iframe under IE9 and IE10.

See this KB article for additional information and examples: http://www.telerik.com/support/kb/aspnet-ajax/window/modal-radwindow-in-radwindow-in-ie9-and-ie10.aspx .

There are several possible workarounds:
1) remove the Modal feature.
2) Replace the opening logic with the one from this thread ( http://www.telerik.com/community/forums/aspnet-ajax/window/opening-radwindow-from-the-server.aspx ) and add a small timeout before showing the RadWindow. Even 0ms could suffice so the browser has an active element
3) Replace the RadAjaxPanel with an ASP UpdatePanel with UpdateMode set to Conditional
4) Add a function that will provide a focused element and call it in the OnClientBeforeShow event of the RadWindow
5) Add that function and call it in the ResponseScripts of the RadAjaxPanel
 The function could look like this: function fixIE() { document.documentElement.focus();} where, of course, you can focus some other element on the page.

A sample is attached.

Currently the video does not play, only audio is heard. If autosizing is disabled the video functions properly.
A possible workaround is to disable autosizing and manually call the autosize() method when the page is loaded for all other browsers:

<telerik:RadWindow runat="server" ID="rw1" VisibleOnPageLoad="true" NavigateUrl="PlayVideo.aspx"
    AutoSize="false" Width="700" Height="500" OnClientPageLoad="OnClientPageLoad">
</telerik:RadWindow>

 and

function OnClientPageLoad(sender, args)
{
    setTimeout(function ()
    {
        if (!$telerik.isMobileSafari)
        {
            sender.autoSize(false);
        }
    }, 0);
}

When the RenderMode of the RadWindowManager is set to "Auto", the embedded dialogs of the RadWindowManager do not have their resources loaded. For the time being the  RenderMode  must be set either to Classic or to Lightweight.

The content of the RadWindows overflows the available area when the control is used in LightWeight render mode in IE. Also the width of the window is increased with 14px.

image - http://screencast.com/t/vQqM9jLRy6uy

The manually set height of RadWindow is not persisted after PostBack if the control's ShowContentDuringLoad property is set to False. The issue is reproducible in IE9.

Video: http://screencast.com/t/ChvvBVzst

Workaround: Set ShowContentDuringLoad="true" when the current browser is IE:
    <button onclick="OpenRadWindow();return false;" class="Button" style="width: 190px"> Show popup window</button>
    <script type="text/javascript">
        function OpenRadWindow() {
            var oManager = GetRadWindowManager();
            oWind = oManager.getWindowByName("RadWindow1");
            //workaround
            if ($telerik.isIE)
                oWind.add_pageLoad(pageLoaded);
            oWind.show();
        }

        function pageLoaded(oWind) {
            oWind.set_showContentDuringLoad(true);
        }
    </script>

Currently setSize() works for popups that are already shown. If setSize() is called before show() (or radopen() or open() from a RadWindowManager) the new size will not be respected on subsequent iterations.

After added this code window close button stop working.

if we remove these three properties it works fine
        oWnd.SetWidth(width);
        oWnd.SetHeight(height);
        oWnd.center();


function openWin(url) {
        var oWnd = radopen(url, "RadWindow22");
        oWnd.SetWidth(width);
        oWnd.SetHeight(height);
        oWnd.center();
    }

Possible workarounds:
1) the following CSS rule:
		.rwExternalContent iframe
		{
			height: 100%;
		}

OR

2) some JavaScript attached to the OnClientPageLoad event of the control:
			function OnClientPageLoad(sender)
			{
				sender.get_contentFrame().style.height = "100%";
			}

With the classic render mode this allows the developer to always position the popup according to a given target with a given offset.
With the lightweight render mode the current bounds are returned instead of the offsets set by the developer.

The following example always shows a RadWindow according to its offset element instead of only the first time:
						oWindow = $find("<%=winTest2.ClientID%>");
						oWindow.show();
						if (oWindow.get_offsetElementID())
						{
							offsetElementBounds = $telerik.getBounds($get(oWindow.get_offsetElementID()));
							oWindow.moveTo(offsetElementBounds.x + oWindow.get_left(), offsetElementBounds.y + oWindow.get_top());
						}
This will not work as expected with the Lightweight render mode, because the popup will move additionally with its width and height.

When the following RadWindow's propertis are set - AutoSize="true and  RenderMode="Lightweight", the title's width of the RadWindow is 1px. The workaround is to use either RenderMode="Classic" or to override the title's width:

    <style type="text/css">
        h6.rwTitle {
            width: 60% !important;
        }
    </style>

I was using a RadWindowManager with PreserveClientState=True for the purpose of maintaining the size of the RadWindow following postbacks to the server (the user was allowed to resize the RadWindow).  I had javascript to adjust the layout of the controls inside of the RadWindow based on the RadWindow size.  

Following a postback, there was no way to know when the RadWindow's size had been adjusted back to the user's setting because there are no events that indicate when the client state has been restored.  I would like to request that you add an OnClientStateRestored event to the RadWindowManager so that we can execute code once the layout of the RadWindow is finalized following a postback.

The Window will not open in the center of the screen if it was already opened once and the page has been scrolled. It seems that the Window keeps opening at the same position initially was opened, hence it could open out of screen bounds.

Steps & Code for Reproduction

1. Copy/Paste the Code from below and Load the page
2. Click on the Button, the Window will open at the center
3. Scroll toward the top of the page until the button is barely visible
4. Click the button again. At this point, the Window will open out of the screen boundaries, in its initial position

Code

<style>
    .mydiv {
        margin: 2000px 100px;
    }
</style>

<telerik:RadWindow ID="RadWindow1" runat="server">
    <ContentTemplate>
        <h3>RadWindow1 Content</h3>
    </ContentTemplate>
</telerik:RadWindow>

<script>
    function ShowEditForm(sender, args) {
        var wnd = $find("<%= RadWindow1.ClientID %>");
        wnd.show();
    }
    Sys.Application.add_load(function () {
        setTimeout(function () {
            $telerik.$('.mydiv')[0].scrollIntoView();
        }, 100)
    });  
</script>

<div class="mydiv">
    <telerik:RadButton runat="server" ID="RadButton1" Text="OpenWindow" AutoPostBack="false" OnClientClicked="ShowEditForm" />
</div>