"filled in" should optionally not ignore "lip style"

[avxmw]

Trying to make a box with a flat top to then cut the shapes for my screwdrivers I noticed I can not fill the box completely, but the lip always remains. I'm trying to make a uniform height without boundaries and for this the lip is in the way.

As such I'd like to request an option to actually fill in everything as cutting of the lip obviously reduces total height.