Hi,
Is this floor plan view symbolic or projected? In case it's your own 2D symbol for the window we see, omit the wall parts from the 2D representation. I guess you'd like to represent that at the floor plan cut the window is narrower than it's full width. To represent this you'll need a little scripting using the WALLHOLE2 GDL command. This way you can tell ArchiCAD about the exact opening size you want to get.
HTH,
Zsolt Táskai
ArchiCAD Development - GDL Team
AC13, AC14 and upwards...