The 2012.1.507.40 version represents one of our internal builds. The latest internal builds contain only assemblies as a preview of what's (and will be) fixed and we provide these to our customers to verify that the issues have been successfully addressed. The Latest Internal Builds are not of the quality of the official releases and therefore we do not encourage our customers to use them in production.
This is why I would suggest that you wait for the upcoming Q2 release and use in production the official assemblies that will contain all the changes included in the 2012.1.507.40 internal build. Bit if, in the meantime, you need the latest internal builds of our controls, you can download them from here
All the best,
the Telerik team
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