The scrollbar usually appears when the RadDock has fixed height and there is not enough space to display all of its content.
I tried to reproduce your problem by creating a dock and adding a content dynamically, but to no avail. Please compare the attached sample with your actual project and check if there are differences in the setup. Here
you can check the behavior of the dock on my end.
I would suggest checking if there are custom styles on the page that are affecting the skins of RadDock. If the problem persists please open a support ticket
and modify the attached page in order to match your scenario. In case this is not possible, you can also send a simple, runnable page
that isolates the problem so that I can inspect it locally and provide a concrete solution.
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