Index: trunk/src/obj_arc_ui.c
===================================================================
--- trunk/src/obj_arc_ui.c	(revision 5281)
+++ trunk/src/obj_arc_ui.c	(revision 5282)
@@ -26,15 +26,41 @@
 /* Arc UI logics */
 
 #include "config.h"
+#include <math.h>
 #include "obj_arc_ui.h"
 #include "obj_arc.h"
 #include "box.h"
 
+
 #include <stdio.h>
 
 void pcb_arc_ui_move_or_copy(pcb_crosshair_t *ch)
 {
-	fprintf(stderr, "Moving arc endpoint: not yet implemented\n");
+	int *end_pt = ch->AttachedObject.Ptr3;
+	pcb_arc_t *arc = (pcb_arc_t *) pcb_crosshair.AttachedObject.Ptr2;
+	pcb_angle_t start = arc->StartAngle, delta = arc->Delta;
+
+	if (end_pt == NULL) {
+		fprintf(stderr, "Moving arc endpoint: start point not yet implemented %p\n", end_pt);
+	}
+	else {
+		double new_delta, new_end = atan2(-(ch->Y - arc->Y), (ch->X - arc->X)) * 180.0 / M_PI + 180.0;
+		if (delta < 0)
+			new_end -= 360.0;
+		fprintf(stderr, "delta: %f abs-end: %f new-abs: %f new-delta: %f\n", delta, start+delta, new_end, new_end-start);
+		new_delta = new_end-start;
+		if (delta > 0) {
+			if (new_delta < 0)
+				new_delta += 360.0;
+		}
+		else {
+			if (new_delta > 0)
+				new_delta -= 360.0;
+		}
+		delta = new_delta;
+	}
+
+	pcb_gui->draw_arc(ch->GC, arc->X, arc->Y, arc->Width, arc->Height, start, delta);
 }
 
 int pcb_obj_ui_arc_point_bbox(int Type, void *Ptr1, void *Ptr2, void *Ptr3, pcb_box_t *res)