The RadHtmlPlaceholder control gets misplaced when displayed inside a RadWindow in a zoomed browser. The issue can be reproduced in the HtmlPlaceholder WindowIntegration demo example.

The placeholder disappears if it's in a RadPane and you close another RadPane

Not measured correctly when no width/height is specified.

When the user navigates in a page displayed in the placeholder and then it is removed and added in the visual tree (when in RadDocking for example) the original SourceUrl is displayed while ideally this should be the page that the user has navigated to.
Update: You can fix this by setting the HTMLPlaceholder's KeepContentInMemory property to True.

This only happens in IE8.  IE9, Chrome, FF3 and FF4 all work okay.  As soon as the componenet is set to visible the scrollbar appears because something has been added to the body html.  The suggested workaround to have the body style overflow set to hidden

MouseWheel does not work when setting an HtmlSource.

Does not resize correctly in IE when surrounded by GridSplitters

When displayed inside a RadWindow, if the window is moved outside the browser, the placeholder gets cut off.
This issue also appears if initally the left side of RadWindow is positioned outside the browser.

When placed in scrollviewer and browser is resized in order to appear the scrollbar, HTMLPlaceHodler doesn`t render correctly. The issue can be reproduced in both scenarios - setting the HtmlSource or SourceUrl property.

The control cannot be placed inside ToolTip ContentTemplate

Height is not calculated properly when the content is wrapped.

OnUnload/OnBeforeUnload do not fire after changing SourceUrl

Incorrect rendering under Mac and Safari

When the HtmlPlaceholder is placed in an ItemTemplate of a ListBox and if the HtmlPlaceholder.KeepContentInMemory is set to True, the control is rendered twice - in the ListBoxItems and in the top left of the page

When PDF is shown, setting visibility to collapsed makes the web page blank

Repro steps:
- Host RadHtmlPlaceholder in a RadWindow
- Set the HtmlPlaceholder content to be a PDF document
- Show the window and then minimize it
- Either restore or maximize the window
- The HtmlPlaceholder content is not rendered

When RadHtmlPlaceholder is removed from the VisualTree doesn't clean up the html frames for it's inner html.

HtmlPlaceholder is renderred incorrectly in ChildWindow

The control is misplaced when you zoom in/out the browser window.

To work this around you can manually calculate and set the top and left positions of the HTML presenter. 

this.htmlPlaceholder.Loaded += (sender, args) => { this.htmlPlaceholder.LayoutUpdated += htmlPlaceholder_LayoutUpdated; };

private void htmlPlaceholder_LayoutUpdated(object sender, EventArgs e)
{
    this.Dispatcher.BeginInvoke(delegate
    {
        double controlTop = GetTop();
        double controlLeft = GetLeft();
 
        htmlPlaceholder.HtmlPresenter.SetStyleAttribute("top", controlTop + "px");
        htmlPlaceholder.HtmlPresenter.SetStyleAttribute("left", controlLeft + "px");
    });           
}