Adding a flat trim to the leading edge of a panel

A customer wanted their new drapery panels with a flat trim running down the leading edge of the panels.  The leading edges are those that meet in the center of the window when the panels are pulled closed. 

There are three things that you must do to get the trim to look its best.  First, you need to pre-shrink both the trim and the panel fabric.  Second, you need to make extra sure that the trim lies flat.  Third, the trim has to be as straight as possible as it is so close to the edge of the panel it will be very easy for anyone to notice that it isn’t straight.