Multiple "cursors" in chart

It would be very nice with an option to add "lines" into the chart. Similar to cursor, but not "attached" to the mouse movement, rather a line you can set in a certain position and it stays there, displaying the timestamp and value of a given tag. 

The user should be able to add and remove any number of lines to the chart. And each line can be dragged into position so they can get more presicion on the line placement. 

So it would look something like the attached screenshot.