The idea is that each Kendo UI Window should be displayed on top of the page content, including Menus. This can be changed if the Menu is inside a higher stacking context, compared to the Window. In other words, locate the Menu's ancestor, which is a direct child of the <body> element, and apply a high-enough z-index, e.g. 20000. Note that this will cause the root Menu items to be displayed over the Window as well, if you drag the Window towards the Menu. I doubt that this is acceptable.
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