Dragging the flightplan route

I was playing around with the FS2004 in-game flightplanner... sometimes when I double click/click on a random point in space, I'll actually manage to winch the route and drag it onto a particular waypoint. This is best when trying to pick hard to find waypoints for the route and then not having to go find the red line to drag, only to lose sight of the waypoint.

 

Anyone actively familiar with how to do it? This and clicking waypoints one time to add to the route (if the line is close enough) seem to be inconsistent. That or how far zoomed in/out appear to have an effect on it.

 

Otherwise I'm looking to use simbrief...

Just use simbrief. A zillion times easier. Then just load it into the sim and voila, no more losing the red route line. :)