Indeed this method will always work as this is one of the main RadWindow methods. More information on the ways to open a RadWIndow is available in this help article:
and the available Client-side API is listed here:
As noted in the first article the radopen method is linked to the RadWindowManager and tries to open a child window of this manager, and since your is not declared there radopen() will create a new instance which will, of course, have none of the content you have in your.
the Telerik team
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