Hello Kenneth Jackson,
I suppose that you want to place a RadButtonElement in a tab of a ToolWindow. If so, please notice that the tab layout of the ToolTabStrip is inverted, so you need to set the Alignment
in order to set the button to the right side in a tab item.
I am attaching a sample project which demonstrates this approach. If you have additional questions, feel free to contact me.
the Telerik team