On the trial of such issue, the proponent of the will shall have the affirmative of the issue and be entitled to all the rights of one occupying such position. The witnesses shall be examined orally before the jury, except where in the circuit court depositions would be admissible; and the testimony taken on the probate of the will shall be admissible if the witnesses who delivered it be dead, out of the state, or have since become incompetent.