move code and add comment

pupil_src/capture/eye.py

@@ -120,10 +120,6 @@ def on_button(window,button, action, mods):
         g_pool.gui.update_button(button,action,mods)
 
 
-    window_update_timer = timer(1/60.)
-    def window_should_update():
-        return next(window_update_timer)
-
 
     def on_pos(window,x, y):
         hdpi_factor = float(glfwGetFramebufferSize(window)[0]/glfwGetWindowSize(window)[0])
@@ -265,6 +261,12 @@ def set_display_mode_info(val):
     fps_graph.update_rate = 5
     fps_graph.label = "%0.0f FPS"
 
+
+    #create a timer to control window update frequency
+    window_update_timer = timer(1/60.)
+    def window_should_update():
+        return next(window_update_timer)
+
     # Event loop
     while not g_pool.quit.value:
         # Get an image from the grabber