When a RadEditor or SPRadEditor in a custom WebPart for SharePoint 2013 is placed in an UpdatePanel or RadAjaxPanel it is not ajaxified and loses its content after a post back.

Native browser behavior is vendor specific and the above issue cannot be replicated with the latest version. Default browser in latest Android versions is Chrome and we recommend using it instead of the older native browser

When the control is modal it should create a second iframe behind the modal background like it creates one behind the popup itself. This will allow the modal background to stay above heavy-weight objects in IE as well.

The sprite images for the RadButton are moved from the "Button" folder to the "Common" folder of the skins, but the Visual Style Builder searches the images in the Button folder.

The workaround is to extract the archive generated by the Visual Style Builder, move the sprites from the Common folder to the Button folder, archive the files again and import them in the Visual Style Builder. This allows you to edit them in the tool and after that you can download the skin and move the sprites back to the Common folder.

In SharePoint 2010 if a site is created with UI version 3 (The MOSS interface) and RadEditor is set as a feature for rich text fields from the site settings. When a page is edited and an additional Content Editor Webpart is added, after editing its content, the RadEditor's content is lost.