The Splitter (and all RadControls as a whole) is made of HTML and as such they obey some rules which are true in general for the technology itself. As every HTML element, in order to calculate correct size in percentages, the Splitter should have only parents with set size (up to a parent with a fixed height). This is why the control has some initially set fixed height (the mentioned 400px), in order to render itself in case its parent height is not properly configured.
Since we cannot change this behavior for the splitter, the only thing left we could do in this case is to iterate through all the parents and set their height explicitly. However this is not a good solution due to many facts, e.g the following ones:
1) It is not a good practice to silently change the rest of the page
2) Any sizes which were set explicitly by the developer will break
3) There are scenarios in which setting 100% height for the parent is wrong, depending on the scenario. You can have splitter set to 100% but its parent can dynamically change size.
4) Iterating through all the parents in the hierarchy will cause performance slow, while simply setting a CSS to the right elements is much better.
Having in mind the above, we think that it is much better to provide resources on how to configure the layout of the Splitter. You can find this described in details in our online demo below:
Resize with Window
I hope that my reply is detailed enough, in case you have additional comments or some suggestions for a better solution, we will be glad to hear it.
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