Here are some quick notes on the raised topics.
- every k-foo="" attribute with an empty (undefined) value will prevent the widget from initializing, this does not apply to specific widgets or attributes. Can you describe a valid use case, which requires using empty k-foo attributes?
- the Splitter's orientation property accepts a string value, so using k-orientation="horizontal" without inner quotes has always been incorrect
- the Editor + Window problem is caused by the fact that the widgets are initialized while outside the DOM, which is not recommended. This has worked in previous versions due to an initialization timeout, which we removed.
On a side note, you may want to include comments from Telerik support staff in this thread too, so that we don't have to duplicate our responses from similar support tickets of yours. Thank you in advance.
Join us on our journey to create the world's most complete HTML 5 UI Framework - download Kendo UI