Don't hover when the cursor is moving fast, to prevent the weird lagging thing.

pygo.py

@@ -7,8 +7,11 @@ import sys
 sys.path.append('lib/')
 
 import os
+import math
+
 import pygame
 from pygame.locals import *
+
 import goban
 
 
@@ -58,6 +61,10 @@ def build_img_res():
     return ret
 
 
+def magnitude(vector):
+    x,y = vector
+    return math.sqrt(x*x + y*y)
+
 
 def main():
     # Basic screen init
@@ -102,9 +109,12 @@ def main():
             row = y / board_inc
             col = x / board_inc
 
-            if x <= board_size:
-                gb.set_hover((row,col))
-            else:
+            if magnitude(event.rel) < 3:
+                if x <= board_size:
+                    gb.set_hover((row,col))
+                else:
+                    gb.clear_hover()
+            elif gb.hover != gb._real_pos((row,col)):
                 gb.clear_hover()
 
         # Place a stone on left-click