--- a/controls/DurationCellEditor.py	Sun Mar 18 19:18:23 2012 +0100
+++ b/controls/DurationCellEditor.py	Sun Mar 18 21:47:58 2012 +0100
@@ -129,15 +129,17 @@
             self.CellControl.PushEventHandler(evt_handler)
 
     def BeginEdit(self, row, col, grid):
+        self.CellControl.Enable()
         self.CellControl.SetValue(self.Table.GetValueByName(row, 'Interval'))
         self.CellControl.SetFocus()
 
     def EndEdit(self, row, col, grid):
         duration = self.CellControl.GetValue()
         old_duration = self.Table.GetValueByName(row, 'Interval')
-        if duration != old_duration:
+        changed = duration != old_duration
+        if changed:
             self.Table.SetValueByName(row, 'Interval', duration)
-            return True
+        self.CellControl.Disable()
         return False
 
     def SetSize(self, rect):

--- a/controls/LocationCellEditor.py	Sun Mar 18 19:18:23 2012 +0100
+++ b/controls/LocationCellEditor.py	Sun Mar 18 21:47:58 2012 +0100
@@ -68,12 +68,15 @@
     Custom cell editor control with a text box and a button that launches
     the BrowseLocationsDialog.
     '''
-    def __init__(self, parent, locations):
+    def __init__(self, parent):
         self._init_ctrls(parent)
-        self.Locations = locations
+        self.Locations = None
         self.VarType = None
         self.Default = False
 
+    def SetLocations(self, locations):
+        self.Locations = locations
+
     def SetVarType(self, vartype):
         self.VarType = vartype
 
@@ -129,16 +132,14 @@
         self.CellControl = None
     
     def Create(self, parent, id, evt_handler):
-        locations = self.Controler.GetVariableLocationTree()
-        if len(locations) > 0:
-            self.CellControl = LocationCellControl(parent, locations)
-        else:
-            self.CellControl = wx.TextCtrl(parent, -1)
+        self.CellControl = LocationCellControl(parent)
         self.SetControl(self.CellControl)
         if evt_handler:
             self.CellControl.PushEventHandler(evt_handler)
 
     def BeginEdit(self, row, col, grid):
+        self.CellControl.Enable()
+        self.CellControl.SetLocations(self.Controler.GetVariableLocationTree())
         self.CellControl.SetValue(self.Table.GetValueByName(row, 'Location'))
         if isinstance(self.CellControl, LocationCellControl):
             self.CellControl.SetVarType(self.Controler.GetBaseType(self.Table.GetValueByName(row, 'Type')))
@@ -147,10 +148,11 @@
     def EndEdit(self, row, col, grid):
         loc = self.CellControl.GetValue()
         old_loc = self.Table.GetValueByName(row, 'Location')
-        if loc != old_loc:
+        changed = loc != old_loc
+        if changed:
             self.Table.SetValueByName(row, 'Location', loc)
-            return True
-        return False
+        self.CellControl.Disable()
+        return changed
     
     def SetSize(self, rect):
         self.CellControl.SetDimensions(rect.x + 1, rect.y,