Some advice on cutting doors...
Since you say it's a french door, I'm assuming it's solid. Be careful cutting hollow-core doors, you can make a real mess of things if you take off to much.
If you have a table saw and at least one other person to help, it will do a nicer job then a hand-held circular saw. In either case use a good, sharp blade. Dull blades bind, burn, and are generally dangerous.
To help reduce splintering, score the the veneer where you are going to cut with a utility knife, run a piece of wide masking tape down the cut line on both side of the door. When you remove the tape, pull it at an angle toward the cut. Also, if you're using a table saw, consider making a zero-clearance insert for this cut. If you're using a circular saw, put a piece of scrap plywood under the cut line.
As somebody else said, make sure to reseal it when you're done.