I have answered your support ticket. For your convenience I have pasted the answer here as well:
"The RadWindow's client-side object exposes getters and setters methods for its properties. For example, you need to use the set_width(value) or set_height(value) methods in order to apply the desired size to the RadWindow object. Alternatively you can use the setSize(width, height) method. More information about the RadWindow's client-side API can be found on this page."
All the best,
the Telerik team
Do you want to have your say when we set our development plans?
Do you want to know when a feature you care about is added or when a bug fixed?
Telerik Public Issue Tracking
system and vote to affect the priority of the items.