is there a HeldBoomBox hook to stop the stream ui from opening. and catch a player opened it?

Most likely the opening is client side, meaning a server side hook would be impossible.

i guess one way would be the onplayerinput.
but dont think there is a way to force the ui to close.

Ts3hosting

i guess one way would be the onplayerinput.
but dont think there is a way to force the ui to close.

OnPlayerInput only works with bound (configurable) keys passed to the server, so as long as that is a standard key used, then maybe.

Setting its Busy flag might work, if you're okay with blocking player input completely.

I went with detecting the active item change and adding/removing mono to the player
then catch the input and used the reload key to bring up the custum ui menu.