The Windows snipping tool has the ability to snip part of the screen. Several screen capture products can also capture just part of the screen. There seems to be a missed opportunity in the gap between sharing a specific program and sharing a full screen of sharing just a custom part of the screen. Being able to by default also zoom this to fill attendee's view would be brilliant. This would help when zeroing in on a specific part of a large slide, or sharing a small part of a large high-resolution screen.