Index: draw_composite.c
===================================================================
--- draw_composite.c	(nonexistent)
+++ draw_composite.c	(revision 8417)
@@ -0,0 +1,88 @@
+/*
+ *                            COPYRIGHT
+ *
+ *  PCB, interactive printed circuit board design
+ *  Copyright (C) 1994,1995,1996, 2003, 2004 Thomas Nau
+ *
+ *  This program is free software; you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License as published by
+ *  the Free Software Foundation; either version 2 of the License, or
+ *  (at your option) any later version.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License
+ *  along with this program; if not, write to the Free Software
+ *  Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
+ *
+ *  Contact addresses for paper mail and Email:
+ *  Thomas Nau, Schlehenweg 15, 88471 Baustetten, Germany
+ *  Thomas.Nau@rz.uni-ulm.de
+ *
+ */
+
+/* Local functions to draw a layer group as a composite of logical layers
+   using positive and negative draw operations. Included from draw.c. */
+
+static void mask_start_sub_(int thin, const pcb_box_t *screen)
+{
+	if (thin)
+		pcb_gui->set_color(Output.pmGC, conf_core.appearance.color.mask);
+	else
+		pcb_gui->use_mask(HID_MASK_CLEAR);
+}
+
+static void mask_start_add_(int thin, const pcb_box_t *screen)
+{
+	if (thin)
+		pcb_gui->set_color(Output.pmGC, "erase");
+	else
+		pcb_gui->use_mask(HID_MASK_SET);
+}
+
+static void mask_start_sub(int thin, const pcb_box_t *screen)
+{
+	if (pcb_gui->mask_invert)
+		mask_start_add_(thin, screen);
+	else
+		mask_start_sub_(thin, screen);
+}
+
+static void mask_start_add(int thin, const pcb_box_t *screen)
+{
+	if (pcb_gui->mask_invert)
+		mask_start_sub_(thin, screen);
+	else
+		mask_start_add_(thin, screen);
+}
+
+static void mask_finish(int thin, const pcb_box_t *screen)
+{
+	if (!thin) {
+		pcb_gui->use_mask(HID_MASK_AFTER);
+		DrawMaskBoardArea(HID_MASK_AFTER, screen);
+		pcb_gui->use_mask(HID_MASK_OFF);
+	}
+}
+
+static void mask_init(int thin, const pcb_box_t *screen, int negative)
+{
+	pcb_gui->use_mask(HID_MASK_INIT);
+
+	if (pcb_gui->mask_invert)
+		negative = !negative;
+
+	if ((!thin) && (negative)) {
+		/* old way of drawing the big poly for the negative */
+		DrawMaskBoardArea(HID_MASK_BEFORE, screen);
+
+		if (!pcb_gui->poly_before) {
+			/* new way */
+			pcb_gui->use_mask(HID_MASK_SET);
+			DrawMaskBoardArea(HID_MASK_SET, screen);
+		}
+	}
+}