Hiding speaker thumbnail during screen sharing.

How do I hide the speaker's thumbnail image from those attending the meeting, while sharing a image or video etc?  This is especially needed when using the share screen alongside the speaker two images side by side) or when the speaker is superimposed onto the shared image. In these share modes there is still a floating thumbnail of the speaker on a mobile device or they appear at the top of the screen along with other participants. It looks silly having two views of the same speaker.

How do I hide the thumbnail view, when the other screen share views of the speakers are being used? 1