Fixed mouse position bug

drawing.js

@@ -12,10 +12,17 @@ var drawing = {
 };
 
 function down(e){
-	line.starting_point.x = e.pageX - this.offsetLeft;
+	var x = e.pageX, y = e.pageY;
-	line.starting_point.y = e.pageY - this.offsetTop;
+	var obj = e.target;
-	line.end_point.x = e.pageX - this.offsetLeft;
+	do {
-	line.end_point.y = e.pageY - this.offsetTop;
+		x -= obj.offsetLeft;
+		y -= obj.offsetTop;
+	} while(obj = obj.offsetParent);
+
+	line.starting_point.x = x;
+	line.starting_point.y = y;
+	line.end_point.x = x;
+	line.end_point.y = y;
 	drawing.active = true;
 
 	drawing.draw_start(line);
@@ -29,8 +36,15 @@ function up(e){
 
 function move(e){
 	if(drawing.active){
-		line.end_point.x = e.pageX - this.offsetLeft;
+		var x = e.pageX, y = e.pageY;
-		line.end_point.y = e.pageY - this.offsetTop;
+		var obj = e.target;
+		do {
+			x -= obj.offsetLeft;
+			y -= obj.offsetTop;
+		} while(obj = obj.offsetParent);
+
+		line.end_point.x = x;
+		line.end_point.y = y;
 
 		drawing.draw_move(line);
 	}