We have already answered to your ticket so I paste the replay for the community below:
Since Q1, 2013 we have introduced a new sprite for RadButton and to match the new sprite positions RadButton base styles were also changed. That will cause custom RadButton skins used with the latest DLL not to work properly as their sprite is out of date compared to the new position in the base CSS file.
The new sprite is introduced in order to improve the work of all controls. As we have several controls with similar UI design, we have decided to have a common sprite to rule them all, instead of several different sprites. When we finish the whole process of migrating the controls to thew new sprite , this will decrease the DLL size vastly.
We know that it will break the Custom Skins, but we hope that you understand this is for good. Now for example by editing only one sprite, you will be able to use it for RadButton, Combo, Treeview etc. So, in order to use your custom skins you will need to rework your sprites based on the ones provided with our latest release. I have also prepared a project that uses old sprites and new base CSS but with overrides from the custom skin to work properly with the old sprite. Is is attached to the project.
Note also, that another breaking change was introduces with the latest release: RadButton and HTML Compliance.
The provided changes do not affect the actual appearance of the controls except for the custom skins which are actually a custom solutions. That is why the introduction of the new sprites for the mentioned controls was not included to the release notes. However, it will be a good idea for the future, in case such changes appears to be present in the release notes.
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