Unless you amend the gdl to isolate the pen used for the shutters in plan view,
1. cover 2D shutter line-work with white masking pen and/or fill
2. Instead of using the shutters that come with the window, use the separate shutter library part. These you can put on a layer that won't show in plan.
Erika
Architect, Consultant
MacBook Pro Retina, 15-inch Yosemite 2.8 GHz Intel Core i7 16 GB 1600 MHz DDR3
Mac OSX 10.11.1
AC5-18
Onuma System
"Implementing Successful Building Information Modeling"