On Row Click event show dropdown in the Row

hi,

I have some rows in my sheet locked and some unlocked rows.

When user clicks on a unlocked row I should be able to enter some information.

I am suppose to populate some dropdowns in that row for him to choose.

How can this be done??

I know when a user clicks a row worksheet change event is call. I can write a function in the worksheet change event to populate values in the dropdown...

I went through some articles, and they say it can be done by hiding and unhiding rows. Does anybody knows how to go about it.

Thanks