When a segment is selected or the popover is displaying data for a segment it would be useful if the segment was displayed in the modal title, for example:
Row Label - for visits in "My Segment"
Showing visitors for visits in "My Segment"
For example this is what it looks like currently, when viewing Row Evolution for "Desktop" devices, for a segment called "From Europe":
What we'd expect is:
Desktop (visits in "From Europe")
Metrics for Device Type: Desktop (visits in "From Europe")
This way the modal/popover would have the full context, and if people take a screenshot, the screenshot would be self-explanatory and clear.