We believe that the tab exception has been fixed with our Latest Internal Build version. You can try with it to see whether it will occur again.
As for the tabbing functionality, currently it will not work inside Row Details since we do not support this mode yet, but we have it in our to do list. In other words, we will create a tabbing mode property that will let you specify whether to enter the row details if you are on the last cell of the parent row or to skip directly to the next row, etc.
Unfortunately, we cannot provide an exact time frame for this new feature.
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