Thank you for contacting us.
We were not able to reproduce this exception in a standard RadRibbonBar scenario.
Please note that if you do not have any tabs in the RadRibbonBar
setting the Expanded
property will cause an error since setting this property is valid only when there is at least one tab in the control. The semantics of this property imply that the content of the selected tab is placed on a popup and the control's height is reduced. The popup is shown each time you click on the corresponding tab without taking place on the form on which the Ribbon Bar resides. As of Q2 2010 we have replaced the null-reference exception with an InvalidOperationException.
Could you please give us some further details on your scenario so that we can find the best way to help you?
the Telerik team
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