Watch a simple way to build and install your own wood trim that also solves a common problem with drywall that extends too far past door and window jambs.
Door jamb not flush with drywall.
In other words the jamb is not at a perfect 90 degree angle to the door and the door hits the jamb not allowing it to completely close.
The hinges or the edge of the door are making contact with the jamb prior to the door completely being closed.
When it comes to frameless doors flush primed door panels are the top choice for many designers due to their versatility.
However you can certainly use it to create a 2 tone look as well where the door panel is different from the wall color.
This is caused by over shimming the door jamb opposite the hinge side.
Flush grooved primed door panels are similar in that they.
Nail through the shims and then trim the shims flush to the outside edge of the casing.
If you have or want to purchase a biscuit jointer they do a nice job of keeping your extensions sturdy and lined up with the jambs.
If not i think your best option is going to be to build the extensions proud of the wall and then bring them down flush with a power planer or belt sander.
The drywall is shaved to allow the casing to sit flat on the wall and on the frame.
They can be shimmed on the outside edge using stock cedar shims every 12 to 15.
The casing door and window frame moldings should be mounted parallel to the drywall not canted in.