Using the .Height property has no effect so I suspect there is some other property to allow it?
The Height property is the right one. But by default, all of the row heights are synchonrized. To allow variable-height rows, you need to set the RowSizing property on the Override to Free.
After defining the Override to free i have defined the DefaultRowHeight = 10
but no change Why ? any other way to increase the height of all the row when it loads