Add option for selected area to follow cursor

[iby]

trafficstars

As suggested by @_holt.

[crcastle]

Here is an example of where this would be helpful. The below GIF (recorded with Gifox) is very wide because there is one line of CLI output that is very long. However, this GIF is difficult to view on mobile because the text is very small.

I'm not sure how "follow cursor" functionality would work, but I'd love to have a way to make a GIF like this easier to view on mobile.

[sparanoid]

+1 for this feature, It would be very useful for demonstrating purpose like @crcastle's use case. We can create a smaller selection when recording for better readability on mobile and keep the file small.