In contrast to the DropDownList the RadComboBox control can not show outside the IFRAME.The main cause for this is the different rendering of the controls that is handled differently by the browser. For instance, the dropdown of the combo box is a div with an ul inside. You can try adding this to a simple page inside a simple iframe and change its position - it will hide but will not go out of the iframe. This is the way browsers handle this scenario and we cannot avoid this. What we have done is to add edge detection for the dropdown element of the combo box that you can enable or disable.
the Telerik team
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