The default wdth and heigh ot RadWindow are 300px and should be rendered with these sizes unless its AutoSize
functionality is not enabled. When the window is auto sized (AutoSize="true") it gets resized depending on its content size - can you, please, verify that this is not the case on your side?
If this is not the case, though, please send us a runnable sample we can replicate the problem with
so we can examine what is causing it on our side.
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