Index: obj_common.h
===================================================================
--- obj_common.h	(revision 27764)
+++ obj_common.h	(revision 27765)
@@ -97,6 +97,7 @@
 	unsigned layer_faded:1;      /* draw layer colors faded */
 	unsigned omit_overlay:1;     /* do not draw overlays (which are useful on screen but normally omitted on exports, except if --as-shown is specified */
 	unsigned partial_export:1;   /* 1 if only objects with the EXPORTSEL flag should be drawn */
+	unsigned no_slot_in_nonmech:1; /* if 1, do not draw slots on non-mechanical layers (e.g. "no slot in copper") */
 	/* WARNING: After adding new fields, make sure to update pcb_xform_add() and pcb_xform_is_nop() below */
 };
 
@@ -110,8 +111,9 @@
 		__dst__->layer_faded |= __src__->layer_faded; \
 		__dst__->omit_overlay |= __src__->omit_overlay; \
 		__dst__->partial_export |= __src__->partial_export; \
+		__dst__->no_slot_in_nonmech |= __src__->no_slot_in_nonmech; \
 	} while(0)
-#define pcb_xform_is_nop(src) (((src)->bloat == 0) && ((src)->layer_faded == 0) && ((src)->omit_overlay == 0) && ((src)->partial_export == 0))
+#define pcb_xform_is_nop(src) (((src)->bloat == 0) && ((src)->layer_faded == 0) && ((src)->omit_overlay == 0) && ((src)->partial_export == 0) && ((src)->no_slot_in_nonmech == 0))
 
 /* Returns true if overlay drawing should be omitted */
 #define pcb_xform_omit_overlay(info) \