[Back In The Saddle]

In NFHS goaltending is defined as: "Goaltending occurs when a player touches the ball during a field-goal try or tap while it is in its downward flight entirely above the basket ring level and has the possibility of entering the basket in flight..."

In your case if a player swats it away after it hits the glass while it's still on its way up, it's a righteous block. Also, if any part of the ball is below the rim or if there is no possibility of it entering the basket, it's fair game. So it would be incorrect to call it goaltending based on it having hit "any part of the backboard" alone.

NCAA is pretty much identical to NFHS.

NBA rules, however, are different. "A Player Shall Not: ...
c. During a field goal attempt, touch a ball after it has touched any part of the backboard above ring level, whether the ball is considered on its upward or downward flight.
d. During a field goal attempt, touch a ball after it has touched the backboard below the ring level and while the ball is on its upward flight.

So according to NBA rules, you'd be right.