This is a known issue in RadImageEditor which has already been logged into our PIT system. You could track its progress here: http://www.telerik.com/support/pits.aspx#/details/Issue=13356
For the time being, you could workaround the problem by setting the ImageEditor's CanvasMode
property to "No
Please, excuse us for the temporary inconveniences.
the Telerik team
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