does not support out of the box the behaviors desired by you. In order to achieve your requirement you will need to write custom code.
Given your last clarifications, it seems that you can explore the option of using the RadDocking
control instead of RadTabControl.
The default behavior of the docking control is to open the tabs on mouse enter. However, with little customization the opening of the tabs can happen on mouse click. This is demonstrated in the attached project with the CustomFlyoutBehavior
However this control also does not have built in functionality to resize the other elements when a tab is opened. The tabs are implemented as popups and for achieving the desired result you can manually resize the desired elements when a tab is opened.
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and share your thoughts.