or
<telerik:RadWindowManager ID="RadWindowManager1" Overlay="true" runat="server" Modal="true" EnableViewState="false" VisibleStatusbar="false" Behaviors="Close,Move,Resize" Skin="skr" EnableEmbeddedSkins="false" OnClientPageLoad="AdjustRadWidow" autoSize="true" ></telerik:RadWindowManager>function AdjustRadWidow() { try { var manager = GetRadWindowManager(); var oWindow = manager.GetActiveWindow(); } catch (err) { var oWindow = GetRadWindow(); } setTimeout(function () { oWindow.autoSize(true); if ($telerik.isChrome || $telerik.isSafari) ChromeSafariFix(oWindow); }, 500);}//fix for Chrome/Safari due to absolute positioned popup not counted as part of the content page layoutfunction ChromeSafariFix(oWindow) { var iframe = oWindow.get_contentFrame(); var body = jQuery('iframe[name=RadWindow1]').contents().find(".content"); if (typeof jQuery(body).html() === 'undefined') { body = jQuery('.content'); } setTimeout(function () { var height = jQuery(body)[0].scrollHeight + 275; var width = jQuery(body)[0].scrollWidth + 70; var iframeBounds = $telerik.getBounds(iframe); var heightDelta = height - iframeBounds.height; var widthDelta = width - iframeBounds.width; if (heightDelta > 0) oWindow.set_height(oWindow.get_height() + heightDelta); if (widthDelta > 0) oWindow.set_width(oWindow.get_width() + widthDelta); oWindow.center(); }, 310);}if textbox.text != null{textbox.backgroundcolor = red;}