So - one cool thing about Rocket.Chat/Chat+ is that you can do screen sharing between multiple persons - like gotomeeting. To use - you must install plugins - either for firefox (https://addons.mozilla.org/en-GB/firefox/addon/rocketchat-screen-share/) or chrome (dont have that link).
Here is how to enable:
start a video chat between you and another party. It does depend on how you have your webrtc setup - if it is not enabled for public rooms- then start a video chat in a direct message between you and another party. after you have started the video chat and the other party has accepted - there will be a few additional buttons that appear. Three red buttons - Stop; Mute Mic; Hide Video - then 2 blue buttons - screen sharing; full screen. Click the screen sharing button. if you have not already installed the appropriate plugin - a popup will appear asking if you want to install the plugin. If you select yes it will open a new browser tab and redirect you to the appropriate extensions page.
After installing extension you must refresh your chat page for extension to kick in. Then- just start a new chat with another party and click the screen share button again. This time a popup will appear showing different windows of things you have open - and it will ask what you want to share. Select your option and that will replace your video with what you want to screen share.
I would highly suggest installing the extensions yourself and taking note of the url for the extensions, then place this info on your chat home page so that users know to install the extensions before attempting to screen share or they have to initiate a whole new video chat.