Looks promising. Lots of small UI/UX things:
1. Wasn't clear how to move objects around (the iconography for the buttons can use some improvement).
2. Delete/erase button is pretty confusing too - again, it wasn't clear how to actually erase something.
3. The bg music on voice chat is unnecessary in my view. I hate that in most conferencing solutions.. :P
4. If conferencing/collaboration is high volume use case, i'd be curious to know why you chose to hide those options under a menu...
Hope this helps.