The size calculation in Kendo Splitter happens from the outside to the inside. You can read more about that in this forum post: http://www.telerik.com/forums/grid-100-height#9AlrQ3unI0a08VEY9RfrxQ. And the thread here might be also useful on the case: http://www.telerik.com/forums/grid-100-height#jMp5aPGYEUad5JxrLMWN0A. Which means that it is the parent elements that control the size of the splitter rather the panes' content.
That said, it is up to further logic to dynamically change the parent's height and resize the splitter according to the content.
Basically, with the grid you need the appropriate event that indicates that it is rendered, like dataBound. And with that event change the document's body's height. Finally, call the splitter's resize() method. You can see an example about that here: http://dojo.telerik.com/ucEQu.
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