Here is a quote of my answer to the support ticket opened on the same subject:
Since the Q3 2012 (2012.3.1114) release of Kendo UI we have added a keyboard support to all widgets in the Web suite. The Calendar widget also have a keyboard support and the described behavior is part of this functionality. When the widget is focused (step 2), the widget will higlight the currect focused date or today's date if nothing is selected. The "k-state-focused" CSS class shows to the end user, which is the current focused date. He can selects the date using the Enter key (check this demo for more information).
If you need to avoid this behavior, you can change the CSS styling of the focused cell. Here is a jsBindemo, which shows how to achieve this.
I will ask you to continue our conversation in the support ticket in order to avoid any duplications.
the Telerik team
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