Hello Henk Jelt,
Normally the TabStrip content wrappers (div.k-content) have no explicit height. The observed problem is possible to occur if they have pixel height and the content cannot fit. In order to enable scrolling, please use
.k-tabstrip > .k-content
On the other hand, the TreeView has the above style applied by design, so if you set an explicit height to its wrapper (div.k-treeview), a scrollbar will appear if needed.
the Telerik team
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