diff --git a/light8/Lightboard.py b/light8/Lightboard.py
--- a/light8/Lightboard.py
+++ b/light8/Lightboard.py
@@ -159,7 +159,10 @@ class Lightboard:
         extlevels = self.slidermapper.get_levels()
         for name, val in extlevels.items():
             if name in self.scalelevels:
-                self.scalelevels[name].set(val)
+                sl = self.scalelevels[name]
+                sl.disable_traces()
+                sl.set(val)
+                sl.recreate_traces()
         
         for lev,lab,oldlev,numlab in zip(levels, self.channel_levels, 
                                          self.oldlevels, 
diff --git a/light8/panels.py b/light8/panels.py
--- a/light8/panels.py
+++ b/light8/panels.py
@@ -135,7 +135,7 @@ class Subpanels:
             # make DoubleVar (there might be one left around from
             # before a refresh)
             if name not in scalelevels:
-                scalelevels[name]=DoubleVar()
+                scalelevels[name]=FancyDoubleVar()
 
             sub.set_slider_var(scalelevels[name])
 
diff --git a/light8/uihelpers.py b/light8/uihelpers.py
--- a/light8/uihelpers.py
+++ b/light8/uihelpers.py
@@ -153,6 +153,27 @@ class Togglebutton(Button):
             self.config(bg=self._origbkg,relief='raised')
         return "break"
 
+
+class FancyDoubleVar(DoubleVar):
+    def __init__(self,master=None):
+        DoubleVar.__init__(self,master)
+        self.callbacklist = {}
+    def trace_variable(self,mode,callback):
+
+        # we build a list of the trace callbacks (the py functrions and the tcl functionnames)
+        id=DoubleVar.trace_variable(self,mode,callback)
+
+        self.callbacklist[id]= [mode,callback]
+
+        return id
+
+    def disable_traces(self):
+        for k,v in self.callbacklist.items():
+            self.trace_vdelete(v[0],k)
+    def recreate_traces(self):
+        for k,v in self.callbacklist.items():
+            self.trace_variable(v[0],v[1])
+
 if __name__=='__main__':
     root=Tk()
     root.tk_focusFollowsMouse()