Index: draw.c
===================================================================
--- draw.c	(revision 25584)
+++ draw.c	(revision 25585)
@@ -1,8 +1,38 @@
 #include "main.h"
+#include "hid.h"
 
 void pcbhl_expose_main(pcb_hid_t *hid, const pcb_hid_expose_ctx_t *region, pcb_xform_t *xform_caller)
 {
+	hle_line_t *l;
+	hle_rtree_it_t it;
+	hle_rtree_box_t qb;
+	pcb_hid_gc_t gc;
 
+	/* announce start of rendering */
+	pcb_gui->render_burst(PCB_HID_BURST_START, &region->view);
+
+	/* The canvas needs to be set up (reset) and put in positive drawing mode */
+	pcb_gui->set_drawing_mode(PCB_HID_COMP_RESET, 1, &region->view);
+	pcb_gui->set_drawing_mode(PCB_HID_COMP_POSITIVE, 1, &region->view);
+
+	/* gc is the pen */
+	gc = pcb_gui->make_gc();
+	pcb_gui->set_color(gc, pcb_color_black);
+
+	/* do an rtree search on the visible region to see what needs to be drawn */
+	qb.x1 = region->view.X1;
+	qb.y1 = region->view.Y1;
+	qb.x2 = region->view.X2;
+	qb.y2 = region->view.Y2;
+	for(l = hle_rtree_first(&it, &design.lines, &qb); l != NULL; l = hle_rtree_next(&it)) {
+		pcb_gui->set_line_width(gc, l->thick);
+		pcb_gui->set_line_cap(gc, pcb_cap_round);
+		pcb_gui->draw_line(gc, l->x1, l->y1, l->x2, l->y2);
+	}
+
+	pcb_gui->set_drawing_mode(PCB_HID_COMP_FLUSH, 1, &region->view);
+	pcb_gui->destroy_gc(gc);
+	pcb_gui->render_burst(PCB_HID_BURST_END, &region->view);
 }
 
 void pcbhl_expose_preview(pcb_hid_t *hid, const pcb_hid_expose_ctx_t *e)
Index: main.c
===================================================================
--- main.c	(revision 25584)
+++ main.c	(revision 25585)
@@ -27,6 +27,26 @@
 
 design_t design;
 
+static void gen_lines(void)
+{
+	int n;
+	for(n = 0; n < 10; n++) {
+		hle_line_t *l = malloc(sizeof(hle_line_t));
+		l->x1 = PCB_MM_TO_COORD(rand() % 100);
+		l->y1 = PCB_MM_TO_COORD(rand() % 100);
+		l->x2 = PCB_MM_TO_COORD(rand() % 100);
+		l->y2 = PCB_MM_TO_COORD(rand() % 100);
+		l->thick = PCB_MM_TO_COORD(rand() % 4);
+
+		l->bbox.x1 = MIN(l->x1, l->x2) - l->thick;
+		l->bbox.y1 = MIN(l->y1, l->y2) - l->thick;
+		l->bbox.x2 = MAX(l->x1, l->x2) + l->thick;
+		l->bbox.y2 = MAX(l->y1, l->y2) + l->thick;
+
+		hle_rtree_insert(&design.lines, l, &l->bbox);
+	}
+}
+
 int main(int argc, char *argv[])
 {
 	const char *gui_name = "gtk2_gdk";
@@ -34,7 +54,10 @@
 	design.hidlib.size_x = PCB_MM_TO_COORD(100);
 	design.hidlib.size_y = PCB_MM_TO_COORD(100);
 	design.hidlib.grid = PCB_MM_TO_COORD(1);
+	hle_rtree_init(&design.lines);
 
+	gen_lines();
+
 	pcb_hidlib_init1(conf_core_init);
 	pcb_hidlib_init2(pup_buildins);
 	gui_act_init();
Index: main.h
===================================================================
--- main.h	(revision 25584)
+++ main.h	(revision 25585)
@@ -3,9 +3,16 @@
 
 #include "global_typedefs.h"
 #include "hidlib.h"
+#include "rtree.h"
 
+typedef struct hle_line_s {
+	hle_rtree_box_t bbox;
+	pcb_coord_t x1, y1, x2, y2, thick;
+} hle_line_t;
+
 typedef struct {
 	pcb_hidlib_t hidlib;
+	hle_rtree_t lines;
 } design_t;
 
 extern design_t design;