Index: trunk/src/layer.c
===================================================================
--- trunk/src/layer.c	(revision 5611)
+++ trunk/src/layer.c	(revision 5612)
@@ -34,6 +34,7 @@
 #include "compat_misc.h"
 #include "undo.h"
 #include "event.h"
+#include "layer_ui.h"
 
 pcb_virt_layer_t pcb_virt_layers[] = {
 	{"invisible",      PCB_LYT_VIRTUAL + 1,  -1,                  PCB_LYT_VIRTUAL | PCB_LYT_INVIS | PCB_LYT_LOGICAL },
@@ -232,6 +233,9 @@
 	if ((Layer >= Data->Layer) && (Layer < (Data->Layer + PCB_MAX_LAYER + 2)))
 		return Layer - Data->Layer;
 
+	if ((Layer >= pcb_uilayer.array) && (Layer < pcb_uilayer.array + vtlayer_len(&pcb_uilayer)))
+		return (Layer - pcb_uilayer.array) | PCB_LYT_UI;
+
 	return -1;
 }
 
@@ -302,6 +306,9 @@
 {
 	unsigned int res = 0;
 
+	if (layer_idx & PCB_LYT_UI)
+		return PCB_LYT_UI | PCB_LYT_VIRTUAL;
+
 	if (layer_idx == pcb_solder_silk_layer)
 		return PCB_LYT_SILK | PCB_LYT_BOTTOM;
 
@@ -547,6 +554,7 @@
 			case PCB_LYT_ANYPROP:
 			case PCB_LYT_UDRILL:
 			case PCB_LYT_PDRILL:
+			case PCB_LYT_UI:
 				return -1; /* do not create virtual layers */
 
 			case PCB_LYT_INTERN:
@@ -620,6 +628,7 @@
 			case PCB_LYT_ANYPROP:
 			case PCB_LYT_UDRILL:
 			case PCB_LYT_PDRILL:
+			case PCB_LYT_UI:
 				return -1; /* do not create virtual layers */
 
 			case PCB_LYT_INTERN:
@@ -930,6 +939,11 @@
 {
 	if ((id >= 0) && (id < pcb_max_copper_layer+2))
 		return &PCB->Data->Layer[id];
+	if (id & PCB_LYT_UI) {
+		id &= ~(PCB_LYT_VIRTUAL | PCB_LYT_UI);
+		if ((id >= 0) && (id < vtlayer_len(&pcb_uilayer)))
+			return &(pcb_uilayer.array[id]);
+	}
 	return NULL;
 }
 
Index: trunk/src/layer.h
===================================================================
--- trunk/src/layer.h	(revision 5611)
+++ trunk/src/layer.h	(revision 5612)
@@ -57,6 +57,8 @@
 	const char *SelectedColor;
 	pcb_attribute_list_t Attributes;
 	int no_drc;                    /* whether to ignore the layer when checking the design rules */
+
+	const char *cookie;            /* for UI layers: registration cookie; NULL for unused UI layers */
 };
 
 
Index: trunk/src/layer_ui.c
===================================================================
--- trunk/src/layer_ui.c	(revision 5611)
+++ trunk/src/layer_ui.c	(revision 5612)
@@ -26,4 +26,48 @@
 
 /* Virtual layers for UI and debug */
 #include "config.h"
+#define GVT_DONT_UNDEF
 #include "layer_ui.h"
+#include <genvector/genvector_impl.c>
+
+vtlayer_t pcb_uilayer;
+
+pcb_layer_t *pcb_uilayer_alloc(const char *cookie, const char *name, const char *color)
+{
+	int n;
+	pcb_layer_t *l;
+
+	if (cookie == NULL)
+		return NULL;
+
+	for(n = 0; n < vtlayer_len(&pcb_uilayer); n++) {
+		l = &pcb_uilayer.array[n];
+		if (l->cookie == NULL) {
+			l->cookie = cookie;
+			goto found;
+		}
+	}
+
+	l = vtlayer_alloc_append(&pcb_uilayer, 1);
+found:;
+	l->cookie = cookie;
+	l->Color = color;
+	l->Name = name;
+	l->On = 1;
+	return l;
+}
+
+void pcb_uilayer_free_all_cookie(const char *cookie)
+{
+	int n;
+	for(n = 0; n < vtlayer_len(&pcb_uilayer); n++) {
+		pcb_layer_t *l = &pcb_uilayer.array[n];
+		if (l->cookie == cookie) {
+#warning TODO: free all objects
+			l->cookie = NULL;
+			l->Color = l->Name = NULL;
+			l->On = 0;
+		}
+	}
+}
+
Index: trunk/src/layer_ui.h
===================================================================
--- trunk/src/layer_ui.h	(revision 5611)
+++ trunk/src/layer_ui.h	(revision 5612)
@@ -26,3 +26,24 @@
 
 /* Virtual layers for UI and debug */
 #include "layer.h"
+
+/* layer vector:  Elem=pcb_layer_t *; init=0 */
+#define GVT(x) vtlayer_ ## x
+#define GVT_ELEM_TYPE pcb_layer_t
+#define GVT_SIZE_TYPE size_t
+#define GVT_DOUBLING_THRS 64
+#define GVT_START_SIZE 4
+#define GVT_FUNC
+#define GVT_SET_NEW_BYTES_TO 0
+#include <genvector/genvector_impl.h>
+#define GVT_REALLOC(vect, ptr, size)  realloc(ptr, size)
+#define GVT_FREE(vect, ptr)           free(ptr)
+#include <genvector/genvector_undef.h>
+
+/* list of all UI layers */
+extern vtlayer_t pcb_uilayer;
+
+pcb_layer_t *pcb_uilayer_alloc(const char *cookie, const char *name, const char *color);
+void pcb_uilayer_free_all_cookie(const char *cookie);
+
+