It seems that the image you are referring to is not properly attached within this thread. Therefore it is hard to assume what is the exact issue you are experiencing. Hence finding the root cause of the problems would be pretty tricky.
Still it is worth mentioning that the official release of Firefox 26 was made on December 10, 2013. Using old version of Telerik controls such as 2013.3.1015 (“2013 Q3”) combined with browser that is released afterwards may lead to some inconsistent behavior. Based on this I would highly recommend that you upgrade your environment to the latest internal build we have released in case you intend using Firefox 26.
In case you tried the suggestions you mentioned below and you have failed to resolve the initial issue best would be if you could share small runnable project
. This will help us further debug your application and advice you further.
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