I am afraid that RadControls for ASP.NET AJAX are not supported in Internet Explorer Quirks Mode as you can see in the Browser Support article
on our website. RadEditor is compliant with XHTML1.1 Transitional
, while Quirks mode suggests the lack of any Doctype Declaration, causing unexpected behavior.
Currently, I could only recommend disabling Quirks Mode (if it meets your project's requirements) either manually, or via a similar meta tag that can be added to the page, which forces IE to use a different document mode:
Note, that you can replace "IE=8" with the browser version that will best suit your needs.
I hope that you will find the provided workaround helpful. If you have any other questions, feel free to contact us.
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