So it was Hosty and his testimony drew no questions from it.
So not many. A few FBI agents informally not expected to comment on it
Google AI says:
“Yes, the windshield from the JFK assassination limousine was brought into the Warren Commission's hearing room and accepted as evidence on March 9, 1964.
The item, designated Commission Exhibit (CE) 351, was carried into the room wrapped in a blanket for examination by the commission members. Secret Service agents, including Roy H. Kellerman, who was in the front seat of the limousine during the shooting, were present to testify.
The windshield was a key piece of physical evidence in the investigation, particularly regarding the path of the bullets. FBI experts determined that an abrasion on the inner surface of the glass was caused by a bullet fragment impacting it from the inside of the car, corroborating the conclusion that all shots came from behind the limousine.
Today, the windshield is preserved as evidence and held by the National Archives. You can view images of the windshield through the National Archives catalog.”
https://www.google.com/search?q=was+the+windshield+from+the+JFK+assassination+limo+displayed+in+the+hearing+room+of+the+Warren+Commission+during+the+hearings&ie=UTF-8&oe=UTF-8&hl=en-us&client=safariSo, it was brought into the room on March 9, 1964 and was still there in May when Hosty testified. I would assume that many other witnesses saw the windshield in that room.