for datagridview,is there a "Initial new row" event?

hi,

   i'd like to ask for datagridview,is there a "Initial new row" event?

   that is to say, when user begin to add a new row, all the value of that row is setted

   i tried to set in dataset the default value of the field, but the weak point is ,in that case, when user add a new row, it is ok(there is default value in the field),but before user editing the new row,if the user click the other row, the content of the new row disappeared.

   any help will be appreciated

best regards

martin