diff --git a/eeshow/Makefile b/eeshow/Makefile
index a049a8b..b5375bb 100644
--- a/eeshow/Makefile
+++ b/eeshow/Makefile
@@ -12,7 +12,7 @@
 
 NAME = eeshow
 OBJS = main.o sch-parse.o sch-render.o lib-parse.o lib-render.o \
-       gui.o \
+       gui.o gui-over.o \
        file.o git-file.o \
        style.o fig.o record.o cro.o diff.o gfx.o dwg.o text.o misc.o
 
diff --git a/eeshow/gui-over.c b/eeshow/gui-over.c
new file mode 100644
index 0000000..deca726
--- /dev/null
+++ b/eeshow/gui-over.c
@@ -0,0 +1,141 @@
+/*
+ * gui-over.c - GUI: overlays
+ *
+ * Written 2016 by Werner Almesberger
+ * Copyright 2016 by Werner Almesberger
+ *
+ * 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.
+ */
+
+/*
+ * Resources:
+ *
+ * http://zetcode.com/gfx/cairo/cairobackends/
+ * https://developer.gnome.org/gtk3/stable/gtk-migrating-2-to-3.html
+ * https://www.cairographics.org/samples/rounded_rectangle/
+ */
+
+#include <stddef.h>
+#include <stdlib.h>
+#include <math.h>
+
+#include <cairo/cairo.h>
+
+#include "util.h"
+#include "gui-over.h"
+
+
+#define	OVER_FONT_SIZE	16
+#define	OVER_BORDER	8
+#define	OVER_RADIUS	6
+#define	OVER_SEP	8
+#define	OVER_X0		10
+#define	OVER_Y0		10
+
+
+struct overlay {
+	const char *s;
+	struct overlay *next;
+};
+
+
+static void rrect(cairo_t *cr, int x, int y, int w, int h, int r)
+{
+	const double deg = M_PI / 180.0;
+
+	cairo_new_path(cr);
+	cairo_arc(cr, x + w - r, y + r, r, -90 * deg, 0);
+	cairo_arc(cr, x + w - r, y + h - r, r, 0, 90 * deg);
+	cairo_arc(cr, x + r, y + h - r, r, 90 * deg, 180 * deg);
+	cairo_arc(cr, x + r, y + r, r, 180 * deg, 270 * deg);
+	cairo_close_path(cr);
+}
+
+
+static void overlay_draw(const struct overlay *over, cairo_t *cr,
+    int *x, int *y)
+{
+	cairo_text_extents_t ext;
+
+	cairo_set_font_size(cr, OVER_FONT_SIZE);
+	cairo_text_extents(cr, over->s, &ext);
+
+	rrect(cr, *x, *y,
+	    ext.width + 2 * OVER_BORDER, ext.height + 2 * OVER_BORDER,
+	    OVER_RADIUS);
+
+	cairo_set_source_rgba(cr, 0.8, 0.9, 1, 0.8);
+	cairo_fill_preserve(cr);
+	cairo_set_source_rgba(cr, 0.5, 0.5, 1, 0.7);
+	cairo_set_line_width(cr, 2);
+	cairo_stroke(cr);
+
+	cairo_set_source_rgb(cr, 0, 0, 0);
+	cairo_move_to(cr, *x + OVER_BORDER, *y + OVER_BORDER + ext.height);
+	cairo_show_text(cr, over->s);
+
+	*y += ext.height + OVER_SEP;
+}
+
+
+void overlay_draw_all(const struct overlay *overlays, cairo_t *cr)
+{
+	const struct overlay *over;
+	int x = OVER_X0;
+	int y = OVER_Y0;
+
+	for (over = overlays; over; over = over->next)
+		overlay_draw(over, cr, &x, &y);
+}
+
+
+struct overlay *overlay_add(struct overlay **overlays, const char *s)
+{
+	struct overlay *over;
+	struct overlay **anchor;
+	
+	over = alloc_type(struct overlay);
+	over->s = stralloc(s);
+
+	for (anchor = overlays; *anchor; anchor = &(*anchor)->next);
+	over->next = NULL;
+	*anchor = over;
+
+	return over;
+}
+
+
+static void overlay_free(struct overlay *over)
+{
+	free((void *) over->s);
+	free(over);
+}
+
+
+void overlay_remove(struct overlay **overlays, struct overlay *over)
+{
+	struct overlay **anchor;
+
+	for (anchor = overlays; *anchor; anchor = &(*anchor)->next)
+		if (*anchor == over) {
+			*anchor = over->next;
+			overlay_free(over);
+			return;
+		}
+	abort();
+}
+
+
+void overlay_remove_all(struct overlay **overlays)
+{
+	struct overlay *next;
+
+	while (*overlays) {
+		next = (*overlays)->next;
+		overlay_free(*overlays);
+		*overlays = next;
+	}
+}
diff --git a/eeshow/gui-over.h b/eeshow/gui-over.h
new file mode 100644
index 0000000..8307073
--- /dev/null
+++ b/eeshow/gui-over.h
@@ -0,0 +1,27 @@
+/*
+ * gui-over.h - GUI: overlays
+ *
+ * Written 2016 by Werner Almesberger
+ * Copyright 2016 by Werner Almesberger
+ *
+ * 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.
+ */
+
+#ifndef GUI_OVER_H
+#define	GUI_OVER_H
+
+#include <cairo/cairo.h>
+
+
+struct overlay;
+
+
+void overlay_draw_all(const struct overlay *overlays, cairo_t *cr);
+struct overlay *overlay_add(struct overlay **overlays, const char *s);
+void overlay_remove(struct overlay **overlays, struct overlay *over);
+void overlay_remove_all(struct overlay **overlays);
+
+#endif /* !GUI_OVER_H */
diff --git a/eeshow/gui.c b/eeshow/gui.c
index 6b885fe..c56b820 100644
--- a/eeshow/gui.c
+++ b/eeshow/gui.c
@@ -30,6 +30,7 @@
 #include "cro.h"
 #include "gfx.h"
 #include "sch.h"
+#include "gui-over.h"
 #include "gui.h"
 
 
@@ -59,8 +60,6 @@ struct gui_sheet {
 	struct gui_sheet *next;
 };
 
-struct overlay;
-
 struct gui_ctx {
 	GtkWidget *da;
 
@@ -149,126 +148,6 @@ static void aoi_click(struct gui_ctx *ctx, int x, int y)
 }
 
 
-/* ----- Overlays ---------------------------------------------------------- */
-
-
-struct overlay {
-	const char *s;
-	struct overlay *next;
-};
-
-
-#define	OVER_FONT_SIZE	16
-#define	OVER_BORDER	8
-#define	OVER_RADIUS	6
-#define	OVER_SEP	8
-#define	OVER_X0		10
-#define	OVER_Y0		10
-
-
-static void rrect(cairo_t *cr, int x, int y, int w, int h, int r)
-{
-	const double deg = M_PI / 180.0;
-
-	// https://www.cairographics.org/samples/rounded_rectangle/
-
-	cairo_new_path(cr);
-	cairo_arc(cr, x + w - r, y + r, r, -90 * deg, 0);
-	cairo_arc(cr, x + w - r, y + h - r, r, 0, 90 * deg);
-	cairo_arc(cr, x + r, y + h - r, r, 90 * deg, 180 * deg);
-	cairo_arc(cr, x + r, y + r, r, 180 * deg, 270 * deg);
-	cairo_close_path(cr);
-}
-
-
-static void overlay_draw(const struct overlay *over, cairo_t *cr,
-    int *x, int *y)
-{
-	cairo_text_extents_t ext;
-
-	cairo_set_font_size(cr, OVER_FONT_SIZE);
-	cairo_text_extents(cr, over->s, &ext);
-
-	rrect(cr, *x, *y,
-	    ext.width + 2 * OVER_BORDER, ext.height + 2 * OVER_BORDER,
-	    OVER_RADIUS);
-
-	cairo_set_source_rgba(cr, 0.8, 0.9, 1, 0.8);
-	cairo_fill_preserve(cr);
-	cairo_set_source_rgba(cr, 0.5, 0.5, 1, 0.7);
-	cairo_set_line_width(cr, 2);
-	cairo_stroke(cr);
-
-	cairo_set_source_rgb(cr, 0, 0, 0);
-	cairo_move_to(cr, *x + OVER_BORDER, *y + OVER_BORDER + ext.height);
-	cairo_show_text(cr, over->s);
-
-	*y += ext.height + OVER_SEP;
-}
-
-
-static void overlay_draw_all(const struct gui_ctx *ctx, cairo_t *cr)
-{
-	const struct overlay *over;
-	int x = OVER_X0;
-	int y = OVER_Y0;
-
-	for (over = ctx->overlays; over; over = over->next)
-		overlay_draw(over, cr, &x, &y);
-}
-
-
-static struct overlay *overlay_add(struct gui_ctx *ctx, const char *s)
-{
-	struct overlay *over;
-	struct overlay **anchor;
-	
-	over = alloc_type(struct overlay);
-	over->s = stralloc(s);
-
-	for (anchor = &ctx->overlays; *anchor; anchor = &(*anchor)->next);
-	over->next = NULL;
-	*anchor = over;
-
-	return over;
-}
-
-
-static void overlay_free(struct overlay *over)
-{
-	free((void *) over->s);
-	free(over);
-}
-
-
-static void overlay_remove(struct gui_ctx *ctx, struct overlay *over)
-{
-	struct overlay **anchor;
-
-	for (anchor = &ctx->overlays; *anchor; anchor = &(*anchor)->next)
-		if (*anchor == over) {
-			*anchor = over->next;
-			overlay_free(over);
-			redraw(ctx);
-			return;
-		}
-	abort();
-}
-
-
-static void overlay_remove_all(struct gui_ctx *ctx)
-{
-	struct overlay *next;
-
-	while (ctx->overlays) {
-		next = ctx->overlays->next;
-		overlay_free(ctx->overlays);
-		ctx->overlays = next;
-	}
-	redraw(ctx);
-}
-
-
 /* ----- Rendering --------------------------------------------------------- */
 
 
@@ -287,7 +166,7 @@ static gboolean on_draw_event(GtkWidget *widget, cairo_t *cr,
 	y = -(sheet->ymin + ctx->y) * f + alloc.height / 2;
 	cro_canvas_draw(sheet->gfx_ctx, cr, x, y, f);
 
-	overlay_draw_all(ctx, cr);
+	overlay_draw_all(ctx->overlays, cr);
 
 	return FALSE;
 }
@@ -473,7 +352,7 @@ static void set_sheet(struct gui_ctx *ctx, struct gui_sheet *sheet)
 	if (sheet->prev == sheet)
 		sheet->prev = NULL;
 	ctx->curr_sheet = sheet;
-	overlay_remove_all(ctx);
+	overlay_remove_all(&ctx->overlays);
 	zoom_to_extents(ctx);
 }
 
@@ -556,7 +435,7 @@ static void select_subsheet(struct gui_ctx *ctx, void *user)
 		if (sheet->sch == obj->u.sheet.sheet) {
 			sheet->prev = ctx->curr_sheet;
 			set_sheet(ctx, sheet);
-			overlay_add(ctx, obj->u.sheet.name);
+			overlay_add(&ctx->overlays, obj->u.sheet.name);
 			return;
 		}
 	abort();