diff --git a/eeshow/gui/common.h b/eeshow/gui/common.h
index bfe2f3e..dd2f1d3 100644
--- a/eeshow/gui/common.h
+++ b/eeshow/gui/common.h
@@ -145,6 +145,8 @@ void show_history(struct gui_ctx *ctx, enum selecting sel);
 
 /* gui.c */
 
+extern bool use_delta;
+
 struct gui_sheet *find_corresponding_sheet(struct gui_sheet *pick_from,
      struct gui_sheet *ref_in, const struct gui_sheet *ref);
 void mark_aois(struct gui_ctx *ctx, struct gui_sheet *sheet);
diff --git a/eeshow/gui/render.c b/eeshow/gui/render.c
index 3bf1db9..23363e0 100644
--- a/eeshow/gui/render.c
+++ b/eeshow/gui/render.c
@@ -18,11 +18,13 @@
 #include <gtk/gtk.h>
 
 #include "misc/util.h"
+#include "gfx/style.h"
 #include "gfx/cro.h"
 #include "gfx/gfx.h"
 #include "kicad/sch.h"
 #include "kicad/delta.h"
 #include "gfx/diff.h"
+#include "gfx/diff.h"
 #include "gui/aoi.h"
 #include "gui/over.h"
 #include "gui/common.h"
@@ -37,6 +39,9 @@
 #define GLABEL_HIGHLIGHT_PAD	6
 
 
+bool use_delta = 0;
+
+
 /* ----- Helper functions -------------------------------------------------- */
 
 
@@ -170,13 +175,12 @@ static gboolean on_draw_event(GtkWidget *widget, cairo_t *cr,
 		    ctx->new_hist->sheets, ctx->curr_sheet);
 		highlight_glabel(ctx, sheet, cr, x, y, f);
 		cro_canvas_draw(sheet->gfx_ctx, cr, x, y, f);
-	} else {
-#if 0
+	} else if (use_delta) {
 		/* @@@ fix geometry later */
 		cro_canvas_draw(ctx->delta_ab.gfx_ctx, cr, x, y, f);
 		cro_canvas_draw(ctx->delta_a.gfx_ctx, cr, x, y, f);
 		cro_canvas_draw(ctx->delta_b.gfx_ctx, cr, x, y, f);
-#endif
+	} else {
 		hack(ctx, cr, x, y, f);
 	}
 
@@ -216,12 +220,12 @@ void render_sheet(struct gui_sheet *sheet)
 
 void render_delta(struct gui_ctx *ctx)
 {
-#if 0
+#if 1
 	/* @@@ needs updating for curr/last vs. new/old */
 	struct sheet *sch_a, *sch_b, *sch_ab;
-	const struct gui_sheet *a = ctx->curr_sheet;
-	const struct gui_sheet *b = find_corresponding_sheet(
-	    ctx->last_hist->sheets, ctx->curr_hist->sheets, ctx->curr_sheet);
+	struct gui_sheet *a = ctx->curr_sheet;
+	struct gui_sheet *b = find_corresponding_sheet(
+	    ctx->old_hist->sheets, ctx->new_hist->sheets, ctx->curr_sheet);
 
 	sch_a = alloc_type(struct sheet);
 	sch_b = alloc_type(struct sheet);
@@ -242,8 +246,6 @@ void render_delta(struct gui_ctx *ctx)
 
 	// @@@ clean up when leaving sheet
 #endif
-	struct gui_sheet *b = find_corresponding_sheet(
-	    ctx->old_hist->sheets, ctx->new_hist->sheets, ctx->curr_sheet);
 
 	if (!b->rendered) {
 		render_sheet(b);
diff --git a/eeshow/gui/sheet.c b/eeshow/gui/sheet.c
index 74bb5be..6f77756 100644
--- a/eeshow/gui/sheet.c
+++ b/eeshow/gui/sheet.c
@@ -522,6 +522,11 @@ static void sheet_key(void *user, int x, int y, int keyval)
 		redraw(ctx);
 		break;
 
+	case GDK_KEY_a:
+		use_delta = !use_delta;
+		redraw(ctx);
+		break;
+
 	case GDK_KEY_n:
 		ctx->diff_mode = diff_new;
 		redraw(ctx);