Text on shared screens often cannot be seen well, so add features to maximize shared screen

Add the ability isolated and view only one shared screen.
Do not make this option take over the user's display; can't take notes then!
Hide 'channel' list and users list. Tear off these menus, or putting user webcams across the top should be considered as well. 

Business users will need to maximize the size of the shared screen when someone is demonstrating use of an application/coding. Being able to read text, and see UI icons/menus within the presentation clearly is a must.
Displays are often very wide, and inexperienced presenters often don't know they should plan their content to be presented at a lower resolution than they normally work.
The problem is worse for older audience members who keep their own displays at a low resolution so they can read OS/App UI elements well. One can increase text size, but menus the height of a sesame seed are a tad hard to read!