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I also have the same problem in 4.1.3 - none of the above fixes work - if i tab from one cell to another the editor in the cells looses focus.
If you have a large site with a lot of Dom Elements the Problem occurs every time you tab from one cell to another - so this is realy a BIG bug for me.
Same. Both 4.1.2a and 4.1.3, it's making an otherwise clean user experience feel very clunky and amateurish to our test users.
Hoping like mad that this gets sorted before we go live in July.