Use case or problem
Most standard text-editors provide the standard functionality of selecting a line of text when the user clicks on a line number — to the point where this is basic expected functionality of the line numbers beyond mere representational display.
Proposed solution
In edit mode, when line numbers are displayed, the default behavior (perhaps with an option to turn this off for anyone who doesn‘t like it for some idiosyncratic reason) should be for clicking the line-number to select that entire line of text.
Current workaround (optional)
manually selecting the entire line