If you are in a Collaborate session, and you want to share something that is open on your computer, from the right-hand side menu, select the Share Content tab and select Share Application/Screen. You can then select the application you want to share, such as PowerPoint or Microsoft Excel. If you need to share something in a web browser, have a separate browser window open that contains what you want to share (before you start your session). Select the relevant web browser to share it (not the one with BB Collaborate open).
Selecting the web browser with Collaborate open will give you the infinity/tunnel view shown below. This happens because the screen that you’re sharing is showing the Collaborate window. To resolve this, simply make sure that you’re not sharing the Collaborate window. You can do this by minimising the Collaborate window; however, you won’t be able to see the chat messages or any other information from the session. If you have two monitors, you can move the Collaborate window onto the screen that you’re not sharing. This will allow you to see the chat and share your screen at the same time without the tunnel effect.