Have you ever wanted to get the control property in your code-behind but you can't "see" it? Ok, here is the way to find it.
In this case I am using GridView control which is bind to datasource and has, for example a template field which has custom control let's say Label1 and I want to get it's property "Text".
Dim LabelText As Label = CType(GridView.FindControl("Label1"), Label)
LabelText.Text = "This is the test text for the Label1 control in grid view"
That's it!
P.S.
If you have any questions ask