Such behavior can be observed can be observed in the following cases (that I know of):
- the clicked button is an anchor (i.e., its HTML element is something like <a href="#"></a>), This causes the browser to attempt to scroll so that this anchor is the topmost element, but it is likely that there simply isn't enough content so the change of position is slight
- the page/content that loads after the button is clicked has default focus. The browser attempts to call scrollIntoView() on that element, but it fails to take into account the absolute positioning of the iframe and thinks that the focused element is in the beginning of the page so it tries to scroll (much like an anchor).
The fixes for these situations are as follows:
- remove the default (server) focus and use the Sys.Application.Load event (or any other applicable event when the content is fully rendered) to focus the desired element with a small timeout.
- if you can - simply raise the window.resize event in the appropriate event. Note that this has to happen on the main page, not in the RadWindow context: http://stackoverflow.com/a/15971955/812369.
I hope this helps so you can incorporate the appropriate idea in your actual case.
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