Thank you for reporting this issue. We reviewed the RadGridView control and we can confirm that the reported behavior is actually a bug. We logged it in our Feedback Portal, where you can track it's status. We also updated your Telerik account points as a thanks for your cooperation in reporting this issue.
As a workaround you can define a custom Keyboard Command Provider and clear all the pending commands, when you press Tab.
Please give the suggested workaround a try and let us know how it goes.
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