Optimal row height with merged cells in OpenOffice Calc?

Question

open source

There are two rows, they have a pair of merged cells (by rows).
If in the context menu of both rows select "Optimal row height ..." and check the box "Default" with a value of 0.0, then, provided that the text in the merged cell does not fit in height, the row height does not increase.
Could you tell me, please, how in this case it is possible to make auto-selection of height?

Answer 1

By double clicking on the delimiter in the row header?
PS Your method works for me too.

Answer 2

3.2