To reproduce: Design time steps: 1. Add a UserControl with size bigger than the Form. 2. Add a RadCollapsiblePanel to the UserControl and set its IsExpanded property to false. 3. Position the RadCollapsiblePanel to the right most place of the UserControl. Thus, when you drag and drop the UserControl onto the form, the RadCollapsiblePanel is not visible. Run time steps: 4. Run the application and resize the form so you can see the RadCollapsiblePanel. 5. Click the arrow to expand the panel. As a result its location is changed. Workaround: set the IsExpanded property to false at run time.