diff --git a/smx-config/App.config b/smx-config/App.config
index fba0990..0cbd0a0 100644
--- a/smx-config/App.config
+++ b/smx-config/App.config
@@ -13,6 +13,9 @@
             <setting name="LaunchOnStartup" serializeAs="String">
                 <value>False</value>
             </setting>
+            <setting name="AuxSensors" serializeAs="String">
+                <value />
+            </setting>
         </smx_config.Properties.Settings>
     </userSettings>
 </configuration>
diff --git a/smx-config/Helpers.cs b/smx-config/Helpers.cs
index 177d049..5b52770 100644
--- a/smx-config/Helpers.cs
+++ b/smx-config/Helpers.cs
@@ -381,6 +381,7 @@ namespace smx_config
     // on the user's settings.  This handles managing which sensors each slider controls.
     static class ThresholdSettings
     {
+        [Serializable]
         public struct PanelAndSensor
         {
             public PanelAndSensor(int panel, int sensor)
@@ -408,10 +409,75 @@ namespace smx_config
             // are then synced to the other panels.
             { "cardinal",   7 },
             { "corner",     2 },
+
+            // The aux threshold allows giving a list of specific sensors different thresholds.
+            { "aux",        -1 },
         };
 
+        // Save and load the list of aux sensors to settings.  These aren't saved to the pad, we just
+        // keep them in application settings.
+        static List<PanelAndSensor> cachedAuxSensors;
+        static public void SetAuxSensors(List<PanelAndSensor> panelAndSensors)
+        {
+            List<object> result = new List<object>();
+            foreach(PanelAndSensor panelAndSensor in panelAndSensors)
+            {
+                List<int> panelAndSensorArray = new List<int>() { panelAndSensor.panel, panelAndSensor.sensor };
+                result.Add(panelAndSensorArray);
+            }
+
+            Properties.Settings.Default.AuxSensors = SerializeJSON.Serialize(result);
+            Properties.Settings.Default.Save();
+
+            // Clear the cache.  Set it to null instead of assigning panelAndSensors to it to force
+            // it to re-parse at least once, to catch problems early.
+            cachedAuxSensors = null;
+        }
+
+        // Return the sensors that are controlled by the aux threshold slider.  The other
+        // threshold sliders will leave these alone.
+        static public List<PanelAndSensor> GetAuxSensors()
+        {
+//                Properties.Settings.Default.AuxSensors = "[[0,0], [1,0]]";
+            // This is only ever changed with calls to SetSavedAuxSensors.
+            if(cachedAuxSensors != null)
+                return Helpers.DeepClone(cachedAuxSensors);
+
+            List<PanelAndSensor> result = new List<PanelAndSensor>();
+            if(Properties.Settings.Default.AuxSensors == "")
+                return result;
+
+            try {
+                // This is a list of [panel,sensor] arrays:
+                // [[0,0], [0,1], [1,0]]
+                List<object> sensors = SMXJSON.ParseJSON.Parse<List<object>>(Properties.Settings.Default.AuxSensors);
+                foreach(object panelAndSensorObj in sensors)
+                {
+                    List<object> panelAndSensor = (List<object>) panelAndSensorObj;
+                    int panel = panelAndSensor.Get(0, -1);
+                    int sensor = panelAndSensor.Get(1, -1);
+                    if(panel == -1 || sensor == -1)
+                        continue;
+
+                    result.Add(new PanelAndSensor(panel, sensor));
+                }
+            } catch(ParseError) {
+                return result;
+            }
+
+            cachedAuxSensors = result;
+                // SetAuxSensors(result); // XXX
+
+            // SetSavedAuxSensors(result);
+            return Helpers.DeepClone(cachedAuxSensors);
+        }
+
         static public List<PanelAndSensor> GetControlledSensorsForSliderType(string Type, bool advancedMode)
         {
+            // The aux threshold slider always controls the aux sensors.
+            if(Type == "aux")
+                return GetAuxSensors();
+
             List<PanelAndSensor> result = new List<PanelAndSensor>();
 
             // Check if this slider is shown in this mode.
@@ -432,6 +498,7 @@ namespace smx_config
             // If advanced mode is disabled, save to all panels this slider affects.  The down arrow controls
             // all four cardinal panels.  (If advanced mode is enabled we'll never be a different cardinal
             // direction, since those widgets won't exist.)  If it's disabled, just write to our own panel.
+            List<PanelAndSensor> auxSensors = GetAuxSensors();
             List<int> saveToPanels = new List<int>();
             int ourPanelIdx = panelNameToIndex[Type];
             saveToPanels.Add(ourPanelIdx);
@@ -442,25 +509,17 @@ namespace smx_config
             {
                 for(int sensor = 0; sensor < 4; ++sensor)
                 {
+                    // Ignore sensors controlled by the aux threshold.
                     PanelAndSensor panelAndSensor = new PanelAndSensor(panelIdx, sensor);
+                    if(auxSensors.Contains(panelAndSensor))
+                        continue;
+
                     result.Add(panelAndSensor);
                 }
             }
 
             return result;
         }
-
-        // Return the sensors that are controlled by the aux threshold slider.  The other
-        // threshold sliders will leave these alone.
-        static public List<PanelAndSensor> GetAuxSensors()
-        {
-            List<PanelAndSensor> result = new List<PanelAndSensor>();
-            result.Add(new PanelAndSensor(1,0));
-            result.Add(new PanelAndSensor(1,1));
-            result.Add(new PanelAndSensor(1,2));
-            result.Add(new PanelAndSensor(1,3));
-            return result;
-        }
     }
 
     // This class just makes it easier to assemble binary command packets.
diff --git a/smx-config/MainWindow.xaml b/smx-config/MainWindow.xaml
index 94f884d..12192aa 100644
--- a/smx-config/MainWindow.xaml
+++ b/smx-config/MainWindow.xaml
@@ -931,6 +931,11 @@ instead of only panels with sensors.</TextBlock>
                         <Button Content="Import" Width="50" Padding="5,2" Margin="5,10" Click="ImportSettings" />
                     </StackPanel>
 
+                    <Separator Margin="0,10,0,10" />
+                    <TextBlock HorizontalAlignment="Center"
+                                    xml:space="preserve" FontSize="16">Aux sensors</TextBlock>
+                    <Button Content="Set auxilliary sensors" Width="140" Margin="0 10 0 0" Padding="0 4" Click="SetAuxSensors_Click"/>
+
                     <Separator Margin="0,10,0,10" />
                     <TextBlock HorizontalAlignment="Center"
                                     xml:space="preserve" FontSize="16">Reset all settings</TextBlock>
diff --git a/smx-config/MainWindow.xaml.cs b/smx-config/MainWindow.xaml.cs
index 4ddde3f..b9dc0b6 100644
--- a/smx-config/MainWindow.xaml.cs
+++ b/smx-config/MainWindow.xaml.cs
@@ -17,7 +17,8 @@ namespace smx_config
         {
             InitializeComponent();
 
-            onConfigChange = new OnConfigChange(this, delegate(LoadFromConfigDelegateArgs args) {
+            onConfigChange = new OnConfigChange(this, delegate (LoadFromConfigDelegateArgs args)
+            {
                 LoadUIFromConfig(args);
             });
 
@@ -26,7 +27,7 @@ namespace smx_config
             // to tray to keep playing animations.  If we're not controlling animations,
             // or the firmware supports doing them automatically, don't bug the user
             // with a prompt.
-            Closing += delegate(object sender, System.ComponentModel.CancelEventArgs e)
+            Closing += delegate (object sender, System.ComponentModel.CancelEventArgs e)
             {
                 LoadFromConfigDelegateArgs args = CurrentSMXDevice.singleton.GetState();
 
@@ -70,10 +71,10 @@ namespace smx_config
 
         List<string> thresholdSliderNames = new List<string>()
         {
-            "up-left", "up", "up-right", "left", "center", "right", "down-left", "down", "down-right", "cardinal", "corner",
+            "up-left", "up", "up-right", "left", "center", "right", "down-left", "down", "down-right", "cardinal", "corner", "aux",
         };
 
-        Dictionary<string,string> thresholdToIcon = new Dictionary<string, string>()
+        Dictionary<string, string> thresholdToIcon = new Dictionary<string, string>()
         {
             { "up-left",   "Resources/pad_up_left.png" },
             { "up",        "Resources/pad_up.png" },
@@ -86,11 +87,12 @@ namespace smx_config
             { "down-right","Resources/pad_down_right.png" },
             { "cardinal",  "Resources/pad_cardinal.png" },
             { "corner",    "Resources/pad_diagonal.png" },
+            { "aux",       "Resources/pad_diagonal.png" },
         };
 
         bool IsThresholdSliderShown(string type)
         {
-            bool AdvancedModeEnabled = (bool) AdvancedModeEnabledCheckbox.IsChecked;
+            bool AdvancedModeEnabled = (bool)AdvancedModeEnabledCheckbox.IsChecked;
             SMX.SMXConfig config = ActivePad.GetFirstActivePadConfig();
             bool[] enabledPanels = config.GetEnabledPanels();
 
@@ -108,20 +110,20 @@ namespace smx_config
             // turned back on.
             switch(type)
             {
-            case "up-left":    return  enabledPanels[0];
-            case "up":         return  enabledPanels[1];
-            case "up-right":   return  enabledPanels[2];
-            case "left":       return  enabledPanels[3];
-            case "center":     return  enabledPanels[4];
-            case "right":      return  enabledPanels[5];
-            case "down-left":  return  enabledPanels[6];
-            case "down":       return  enabledPanels[7];
-            case "down-right": return  enabledPanels[8];
+            case "up-left": return enabledPanels[0];
+            case "up": return enabledPanels[1];
+            case "up-right": return enabledPanels[2];
+            case "left": return enabledPanels[3];
+            case "center": return enabledPanels[4];
+            case "right": return enabledPanels[5];
+            case "down-left": return enabledPanels[6];
+            case "down": return enabledPanels[7];
+            case "down-right": return enabledPanels[8];
 
             // Show cardinal and corner if at least one panel they affect is enabled.
-            case "cardinal":   return enabledPanels[3] || enabledPanels[5] || enabledPanels[8];
-            case "corner":     return enabledPanels[0] || enabledPanels[2] || enabledPanels[6] || enabledPanels[8];
-            default:           return true;
+            case "cardinal": return enabledPanels[3] || enabledPanels[5] || enabledPanels[8];
+            case "corner": return enabledPanels[0] || enabledPanels[2] || enabledPanels[6] || enabledPanels[8];
+            default: return true;
             }
         }
 
@@ -153,7 +155,7 @@ namespace smx_config
 
                 ThresholdSlider slider = CreateThresholdSlider(sliderName);
                 DockPanel.SetDock(slider, Dock.Top);
-                slider.Margin = new Thickness(0,8,0,0);
+                slider.Margin = new Thickness(0, 8, 0, 0);
                 ThresholdSliderContainer.Children.Add(slider);
             }
         }
@@ -163,20 +165,20 @@ namespace smx_config
             base.OnApplyTemplate();
 
             // Add our WndProc hook.
-            HwndSource source = (HwndSource) PresentationSource.FromVisual(this);
+            HwndSource source = (HwndSource)PresentationSource.FromVisual(this);
             source.AddHook(new HwndSourceHook(WndProcHook));
 
             Version1.Content = "SMXConfig version " + SMX.SMX.Version();
             Version2.Content = "SMXConfig version " + SMX.SMX.Version();
 
-            AutoLightsColor.StartedDragging += delegate() { showAutoLightsColor.Start(); };
-            AutoLightsColor.StoppedDragging += delegate() { showAutoLightsColor.Stop(); };
-            AutoLightsColor.StoppedDragging += delegate() { showAutoLightsColor.Stop(); };
+            AutoLightsColor.StartedDragging += delegate () { showAutoLightsColor.Start(); };
+            AutoLightsColor.StoppedDragging += delegate () { showAutoLightsColor.Stop(); };
+            AutoLightsColor.StoppedDragging += delegate () { showAutoLightsColor.Stop(); };
 
             CreateThresholdSliders();
 
             // This doesn't happen at the same time AutoLightsColor is used, since they're on different tabs.
-            Diagnostics.SetShowAllLights += delegate(bool on)
+            Diagnostics.SetShowAllLights += delegate (bool on)
             {
                 if(on)
                     showAutoLightsColor.Start();
@@ -184,7 +186,7 @@ namespace smx_config
                     showAutoLightsColor.Stop();
             };
 
-            SetAllPanelsToCurrentColor.Click += delegate(object sender, RoutedEventArgs e)
+            SetAllPanelsToCurrentColor.Click += delegate (object sender, RoutedEventArgs e)
             {
                 // Get the color of the selected color button, and apply it to all other buttons.
                 Color color = selectedButton.getColor();
@@ -206,7 +208,7 @@ namespace smx_config
             ColorButton[] buttons = getColorPickerButtons();
             foreach(ColorButton button in buttons)
             {
-                button.Click += delegate(object sender, RoutedEventArgs e)
+                button.Click += delegate (object sender, RoutedEventArgs e)
                 {
                     ColorButton clickedButton = sender as ColorButton;
                     selectedButton = clickedButton;
@@ -221,7 +223,7 @@ namespace smx_config
             // The user pressed either the "panel colors" or "GIF animations" button.
             bool pressedPanelColors = sender == PanelColorsButton;
 
-            foreach(Tuple<int,SMX.SMXConfig> activePad in ActivePad.ActivePads())
+            foreach(Tuple<int, SMX.SMXConfig> activePad in ActivePad.ActivePads())
             {
                 SMX.SMXConfig config = activePad.Item2;
 
@@ -240,19 +242,19 @@ namespace smx_config
         private void LoadUIFromConfig(LoadFromConfigDelegateArgs args)
         {
             bool EitherControllerConnected = args.controller[0].info.connected || args.controller[1].info.connected;
-            Main.Visibility = EitherControllerConnected? Visibility.Visible:Visibility.Hidden;
-            Searching.Visibility = EitherControllerConnected? Visibility.Hidden:Visibility.Visible;
-            ConnectedPads.Visibility = EitherControllerConnected? Visibility.Visible:Visibility.Hidden;
-            PanelColorP1.Visibility = args.controller[0].info.connected? Visibility.Visible:Visibility.Collapsed;
-            PanelColorP2.Visibility = args.controller[1].info.connected? Visibility.Visible:Visibility.Collapsed;
-            EnableCenterTopSensorCheckbox.Visibility = 
-            P1_Floor.Visibility = 
-            P2_Floor.Visibility = 
-                args.firmwareVersion() >= 5? Visibility.Visible:Visibility.Collapsed;
+            Main.Visibility = EitherControllerConnected ? Visibility.Visible : Visibility.Hidden;
+            Searching.Visibility = EitherControllerConnected ? Visibility.Hidden : Visibility.Visible;
+            ConnectedPads.Visibility = EitherControllerConnected ? Visibility.Visible : Visibility.Hidden;
+            PanelColorP1.Visibility = args.controller[0].info.connected ? Visibility.Visible : Visibility.Collapsed;
+            PanelColorP2.Visibility = args.controller[1].info.connected ? Visibility.Visible : Visibility.Collapsed;
+            EnableCenterTopSensorCheckbox.Visibility =
+            P1_Floor.Visibility =
+            P2_Floor.Visibility =
+                args.firmwareVersion() >= 5 ? Visibility.Visible : Visibility.Collapsed;
 
             // Show the color slider or GIF UI depending on which one is set in flags.
             // If both pads are turned on, just use the first one.
-            foreach(Tuple<int,SMX.SMXConfig> activePad in ActivePad.ActivePads())
+            foreach(Tuple<int, SMX.SMXConfig> activePad in ActivePad.ActivePads())
             {
                 SMX.SMXConfig config = activePad.Item2;
 
@@ -260,8 +262,8 @@ namespace smx_config
                 // If it's not set, show the color slider UI.
                 SMX.SMXConfigFlags flags = config.configFlags;
                 bool usePressedAnimations = (flags & SMX.SMXConfigFlags.AutoLightingUsePressedAnimations) != 0;
-                ColorPickerGroup.Visibility = usePressedAnimations? Visibility.Collapsed:Visibility.Visible;
-                GIFGroup.Visibility = usePressedAnimations? Visibility.Visible:Visibility.Collapsed;
+                ColorPickerGroup.Visibility = usePressedAnimations ? Visibility.Collapsed : Visibility.Visible;
+                GIFGroup.Visibility = usePressedAnimations ? Visibility.Visible : Visibility.Collapsed;
 
                 // Tell the color mode buttons which one is selected, to set the button highlight.
                 PanelColorsButton.Selected = !usePressedAnimations;
@@ -294,7 +296,7 @@ namespace smx_config
                     }
                 }
             }
-            ThresholdWarningText.Visibility = ShowThresholdWarningText? Visibility.Visible : Visibility.Hidden;
+            ThresholdWarningText.Visibility = ShowThresholdWarningText ? Visibility.Visible : Visibility.Hidden;
 
             // If a second controller has connected and we're on Both, see if we need to prompt
             // to sync configs.  We only actually need to do this if a controller just connected.
@@ -355,9 +357,9 @@ namespace smx_config
             foreach(Tuple<int, SMX.SMXConfig> activePad in ActivePad.ActivePads())
             {
                 SMX.SMXConfig config = activePad.Item2;
-                
+
                 bool uploadsSupported = config.masterVersion >= 4;
-                LeaveRunning.Visibility = uploadsSupported? Visibility.Collapsed:Visibility.Visible;
+                LeaveRunning.Visibility = uploadsSupported ? Visibility.Collapsed : Visibility.Visible;
                 break;
             }
         }
@@ -455,12 +457,12 @@ namespace smx_config
             bool TwoControllersConnected = args.controller[0].info.connected && args.controller[1].info.connected;
 
             // Only show the dropdown if two controllers are connected.
-            ConnectedPadList.Visibility = TwoControllersConnected? Visibility.Visible:Visibility.Collapsed;
+            ConnectedPadList.Visibility = TwoControllersConnected ? Visibility.Visible : Visibility.Collapsed;
 
             // Only show the P1/P2 text if only one controller is connected, since it takes the place
             // of the dropdown.
-            P1Connected.Visibility = (!TwoControllersConnected && args.controller[0].info.connected)? Visibility.Visible:Visibility.Collapsed;
-            P2Connected.Visibility = (!TwoControllersConnected && args.controller[1].info.connected)? Visibility.Visible:Visibility.Collapsed;
+            P1Connected.Visibility = (!TwoControllersConnected && args.controller[0].info.connected) ? Visibility.Visible : Visibility.Collapsed;
+            P2Connected.Visibility = (!TwoControllersConnected && args.controller[1].info.connected) ? Visibility.Visible : Visibility.Collapsed;
 
             if(!TwoControllersConnected)
                 return;
@@ -478,7 +480,7 @@ namespace smx_config
 
         private void FactoryReset_Click(object sender, RoutedEventArgs e)
         {
-            foreach(Tuple<int,SMX.SMXConfig> activePad in ActivePad.ActivePads())
+            foreach(Tuple<int, SMX.SMXConfig> activePad in ActivePad.ActivePads())
             {
                 int pad = activePad.Item1;
                 SMX.SMX.FactoryReset(pad);
@@ -494,7 +496,7 @@ namespace smx_config
         private void ExportSettings(object sender, RoutedEventArgs e)
         {
             // Save the current thresholds on the first available pad as a preset.
-            foreach(Tuple<int,SMX.SMXConfig> activePad in ActivePad.ActivePads())
+            foreach(Tuple<int, SMX.SMXConfig> activePad in ActivePad.ActivePads())
             {
                 int pad = activePad.Item1;
                 SMX.SMXConfig config = activePad.Item2;
@@ -505,7 +507,7 @@ namespace smx_config
                 dialog.DefaultExt = ".smxcfg";
                 dialog.Filter = "StepManiaX settings (.smxcfg)|*.smxcfg";
                 bool? result = dialog.ShowDialog();
-                if(result == null || !(bool) result)
+                if(result == null || !(bool)result)
                     return;
 
                 System.IO.File.WriteAllText(dialog.FileName, json);
@@ -521,13 +523,13 @@ namespace smx_config
             dialog.DefaultExt = ".smxcfg";
             dialog.Filter = "StepManiaX settings (.smxcfg)|*.smxcfg";
             bool? result = dialog.ShowDialog();
-            if(result == null || !(bool) result)
+            if(result == null || !(bool)result)
                 return;
 
             string json = Helpers.ReadFile(dialog.FileName);
 
             // Apply settings from the file to all active pads.
-            foreach(Tuple<int,SMX.SMXConfig> activePad in ActivePad.ActivePads())
+            foreach(Tuple<int, SMX.SMXConfig> activePad in ActivePad.ActivePads())
             {
                 int pad = activePad.Item1;
                 SMX.SMXConfig config = activePad.Item2;
@@ -551,13 +553,13 @@ namespace smx_config
             dialog.DefaultExt = ".gif";
             dialog.Filter = "Animated GIF (.gif)|*.gif";
             bool? result = dialog.ShowDialog();
-            if(result == null || !(bool) result)
+            if(result == null || !(bool)result)
                 return;
 
             byte[] buf = Helpers.ReadBinaryFile(dialog.FileName);
-            SMX.SMX.LightsType type = pressed? SMX.SMX.LightsType.LightsType_Pressed:SMX.SMX.LightsType.LightsType_Released;
+            SMX.SMX.LightsType type = pressed ? SMX.SMX.LightsType.LightsType_Pressed : SMX.SMX.LightsType.LightsType_Released;
 
-            foreach(Tuple<int,SMX.SMXConfig> activePad in ActivePad.ActivePads())
+            foreach(Tuple<int, SMX.SMXConfig> activePad in ActivePad.ActivePads())
             {
                 int pad = activePad.Item1;
 
@@ -583,7 +585,7 @@ namespace smx_config
 
             // For firmwares that support it, upload the animation to the pad now.  Otherwise,
             // we'll run the animation directly.
-            foreach(Tuple<int,SMX.SMXConfig> activePad in ActivePad.ActivePads())
+            foreach(Tuple<int, SMX.SMXConfig> activePad in ActivePad.ActivePads())
             {
                 int pad = activePad.Item1;
 
@@ -598,6 +600,12 @@ namespace smx_config
             }
         }
 
+        private void SetAuxSensors_Click(object sender, RoutedEventArgs e)
+        {
+            SetAuxSensors dialog = new SetAuxSensors();
+            dialog.ShowDialog();
+        }
+
         private void UploadLatestGIF()
         {
             // Create a progress window.  Center it on top of the main window.
diff --git a/smx-config/Properties/Settings.Designer.cs b/smx-config/Properties/Settings.Designer.cs
index 6a30787..fad6923 100644
--- a/smx-config/Properties/Settings.Designer.cs
+++ b/smx-config/Properties/Settings.Designer.cs
@@ -12,7 +12,7 @@ namespace smx_config.Properties {
     
     
     [global::System.Runtime.CompilerServices.CompilerGeneratedAttribute()]
-    [global::System.CodeDom.Compiler.GeneratedCodeAttribute("Microsoft.VisualStudio.Editors.SettingsDesigner.SettingsSingleFileGenerator", "15.6.0.0")]
+    [global::System.CodeDom.Compiler.GeneratedCodeAttribute("Microsoft.VisualStudio.Editors.SettingsDesigner.SettingsSingleFileGenerator", "15.9.0.0")]
     internal sealed partial class Settings : global::System.Configuration.ApplicationSettingsBase {
         
         private static Settings defaultInstance = ((Settings)(global::System.Configuration.ApplicationSettingsBase.Synchronized(new Settings())));
@@ -34,5 +34,17 @@ namespace smx_config.Properties {
                 this["LaunchOnStartup"] = value;
             }
         }
+        
+        [global::System.Configuration.UserScopedSettingAttribute()]
+        [global::System.Diagnostics.DebuggerNonUserCodeAttribute()]
+        [global::System.Configuration.DefaultSettingValueAttribute("")]
+        public string AuxSensors {
+            get {
+                return ((string)(this["AuxSensors"]));
+            }
+            set {
+                this["AuxSensors"] = value;
+            }
+        }
     }
 }
diff --git a/smx-config/Properties/Settings.settings b/smx-config/Properties/Settings.settings
index 2d633bc..9f13323 100644
--- a/smx-config/Properties/Settings.settings
+++ b/smx-config/Properties/Settings.settings
@@ -5,5 +5,8 @@
     <Setting Name="LaunchOnStartup" Type="System.Boolean" Scope="User">
       <Value Profile="(Default)">False</Value>
     </Setting>
+    <Setting Name="AuxSensors" Type="System.String" Scope="User">
+      <Value Profile="(Default)" />
+    </Setting>
   </Settings>
 </SettingsFile>
\ No newline at end of file
diff --git a/smx-config/SMXConfig.csproj b/smx-config/SMXConfig.csproj
index 96f395d..4470f57 100644
--- a/smx-config/SMXConfig.csproj
+++ b/smx-config/SMXConfig.csproj
@@ -105,6 +105,9 @@
     <Compile Include="DiagnosticsWidgets.cs" />
     <Compile Include="DoubleSlider.cs" />
     <Compile Include="Helpers.cs" />
+    <Compile Include="SetAuxSensors.xaml.cs">
+      <DependentUpon>SetAuxSensors.xaml</DependentUpon>
+    </Compile>
     <Compile Include="ProgressWindow.xaml.cs">
       <DependentUpon>ProgressWindow.xaml</DependentUpon>
     </Compile>
@@ -123,6 +126,10 @@
       <DependentUpon>MainWindow.xaml</DependentUpon>
       <SubType>Code</SubType>
     </Compile>
+    <Page Include="SetAuxSensors.xaml">
+      <Generator>MSBuild:Compile</Generator>
+      <SubType>Designer</SubType>
+    </Page>
     <Page Include="ProgressWindow.xaml">
       <Generator>MSBuild:Compile</Generator>
       <SubType>Designer</SubType>
diff --git a/smx-config/SetAuxSensors.xaml b/smx-config/SetAuxSensors.xaml
new file mode 100644
index 0000000..58cd4cb
--- /dev/null
+++ b/smx-config/SetAuxSensors.xaml
@@ -0,0 +1,102 @@
+<Window x:Class="smx_config.SetAuxSensors"
+        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
+        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
+        xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
+        xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
+        mc:Ignorable="d"
+        Icon="Resources/window icon.png"
+        Background="#DDD"
+        Height="418" Width="325" ResizeMode="NoResize"
+        xmlns:controls="clr-namespace:smx_config"
+        x:Name="root"
+        Title="Select Auxilliary Sensors"
+        UseLayoutRounding="True">
+    <Window.Resources>
+        <Style x:Key="SensorSelectionButton" TargetType="{x:Type ToggleButton}">
+            <Setter Property="VerticalAlignment" Value="Center" />
+            <Setter Property="Background" Value="#FFDDDDDD"/>
+            <Setter Property="BorderBrush" Value="#FF707070"/>
+            <Setter Property="Foreground" Value="#FFFFFF"/>
+            <Setter Property="BorderThickness" Value="1"/>
+            <Setter Property="Template">
+                <Setter.Value>
+                    <ControlTemplate TargetType="{x:Type controls:SensorSelectionButton}">
+                        <Border x:Name="border" BorderBrush="#000000" BorderThickness="1" SnapsToDevicePixels="true">
+                            <ContentPresenter
+                                SnapsToDevicePixels="true"
+                                Focusable="False"
+                                HorizontalAlignment="Center" VerticalAlignment="Center"
+                            />
+                        </Border>
+
+                        <ControlTemplate.Triggers>
+                            <Trigger Property="IsChecked" Value="False">
+                                <Setter Property="Background" TargetName="border" Value="#FF2020A0"/>
+                            </Trigger>
+                            <Trigger Property="IsChecked" Value="True">
+                                <Setter Property="Background" TargetName="border" Value="#FF00F000"/>
+                            </Trigger>
+                            <Trigger Property="IsPressed" Value="true">
+                                <Setter Property="Background" TargetName="border" Value="#FFC4E5F6"/>
+                                <Setter Property="BorderBrush" TargetName="border" Value="#FF2C628B"/>
+                            </Trigger>
+                        </ControlTemplate.Triggers>
+                    </ControlTemplate>
+                </Setter.Value>
+            </Setter>
+        </Style>
+
+        <Style TargetType="{x:Type controls:SensorSelector}">
+            <Setter Property="Template">
+                <Setter.Value>
+                    <ControlTemplate TargetType="{x:Type controls:SensorSelector}">
+                        <Border Padding="1">
+                            <Grid Width="70" Height="70">
+                                <!-- XXX: the order of these is wrong -->
+                                <controls:SensorSelectionButton x:Name="Sensor0" Style="{StaticResource SensorSelectionButton}" 
+                                    Width="40" Height="13" VerticalAlignment="Top" />
+                                <controls:SensorSelectionButton x:Name="Sensor1" Style="{StaticResource SensorSelectionButton}" 
+                                    Width="40" Height="13" VerticalAlignment="Bottom" />
+                                <controls:SensorSelectionButton x:Name="Sensor2" Style="{StaticResource SensorSelectionButton}" 
+                                    Width="13" Height="40" HorizontalAlignment="Left" />
+                                <controls:SensorSelectionButton x:Name="Sensor3" Style="{StaticResource SensorSelectionButton}" 
+                                    Width="13" Height="40" HorizontalAlignment="Right" />
+                            </Grid>
+                        </Border>
+                    </ControlTemplate>
+                </Setter.Value>
+            </Setter>
+        </Style>        
+
+    </Window.Resources>
+
+    <StackPanel Background="#FFE5E5E5">
+        <TextBlock xml:space="preserve" HorizontalAlignment="Center" Margin="0,15,0,10" TextAlignment="Center" FontSize="16">Select which sensors are controlled
+by the auxilliary threshold.</TextBlock>
+
+        <Grid Width="250" Height="250" Background="#FFAAAAAA" Margin="0,10,0,0">
+            <Grid.ColumnDefinitions>
+                <ColumnDefinition />
+                <ColumnDefinition />
+                <ColumnDefinition />
+            </Grid.ColumnDefinitions>
+            <Grid.RowDefinitions>
+                <RowDefinition />
+                <RowDefinition />
+                <RowDefinition />
+            </Grid.RowDefinitions>
+
+            <controls:SensorSelector Grid.Row="0" Grid.Column="0" Panel="0" Focusable="false" />
+            <controls:SensorSelector Grid.Row="0" Grid.Column="1" Panel="1" Focusable="false" />
+            <controls:SensorSelector Grid.Row="0" Grid.Column="2" Panel="2" Focusable="false" />
+            <controls:SensorSelector Grid.Row="1" Grid.Column="0" Panel="3" Focusable="false" />
+            <controls:SensorSelector Grid.Row="1" Grid.Column="1" Panel="4" Focusable="false" />
+            <controls:SensorSelector Grid.Row="1" Grid.Column="2" Panel="5" Focusable="false" />
+            <controls:SensorSelector Grid.Row="2" Grid.Column="0" Panel="6" Focusable="false" />
+            <controls:SensorSelector Grid.Row="2" Grid.Column="1" Panel="7" Focusable="false" />
+            <controls:SensorSelector Grid.Row="2" Grid.Column="2" Panel="8" Focusable="false" />
+        </Grid>
+
+        <Button x:Name="OK" Content="OK" IsDefault="True" Click="OK_Click" HorizontalAlignment="Center" FontSize="20" Padding="10,4" Margin="0,10,0,0" />
+    </StackPanel>
+</Window>
diff --git a/smx-config/SetAuxSensors.xaml.cs b/smx-config/SetAuxSensors.xaml.cs
new file mode 100644
index 0000000..2e59574
--- /dev/null
+++ b/smx-config/SetAuxSensors.xaml.cs
@@ -0,0 +1,99 @@
+using System;
+using System.Collections.Generic;
+using System.Windows;
+using System.Windows.Controls;
+using System.Windows.Controls.Primitives;
+
+namespace smx_config
+{
+    public class SensorSelectionButton: ToggleButton
+    {
+    }
+
+    // A control with one button for each of four sensors:
+    class SensorSelector: Control
+    {
+        // The panel we're editing (0-8).
+        public static readonly DependencyProperty PanelProperty = DependencyProperty.RegisterAttached("Panel",
+            typeof(int), typeof(SensorSelector), new FrameworkPropertyMetadata(0));
+
+        public int Panel {
+            get { return (int) this.GetValue(PanelProperty); }
+            set { this.SetValue(PanelProperty, value); }
+        }
+
+        ToggleButton[] SensorSelectionButtons = new ToggleButton[4];
+        public override void OnApplyTemplate()
+        {
+            base.OnApplyTemplate();
+
+            for(int sensor = 0; sensor < 4; ++sensor)
+            {
+                int ThisSensor = sensor; // bind
+                SensorSelectionButtons[sensor] = GetTemplateChild("Sensor" + sensor) as ToggleButton;
+                SensorSelectionButtons[sensor].Click += delegate(object sender, RoutedEventArgs e)
+                {
+                    ClickedSensorButton(ThisSensor);
+                };
+            }
+
+            // These settings are stored in the application settings, not on the pad.  However,
+            // we treat changes to this as config changes, so we can use the same OnConfigChange
+            // method for updating.
+            OnConfigChange onConfigChange;
+            onConfigChange = new OnConfigChange(this, delegate(LoadFromConfigDelegateArgs args) {
+                LoadUIFromConfig(args);
+            });
+        }
+
+        private void ClickedSensorButton(int sensor)
+        {
+            // Toggle the clicked sensor.
+            Console.WriteLine("Clicked sensor " + sensor);
+            List<ThresholdSettings.PanelAndSensor> auxSensors = ThresholdSettings.GetAuxSensors();
+            bool enabled = !IsSensorEnabled(auxSensors, sensor);
+
+            if(enabled)
+                auxSensors.Add(new ThresholdSettings.PanelAndSensor(Panel, sensor));
+            else
+                auxSensors.Remove(new ThresholdSettings.PanelAndSensor(Panel, sensor));
+            ThresholdSettings.SetAuxSensors(auxSensors);
+
+            CurrentSMXDevice.singleton.FireConfigurationChanged(this);
+        }
+
+        // Return true if the given sensor is marked as an aux sensor.
+        bool IsSensorEnabled(List<ThresholdSettings.PanelAndSensor> auxSensors, int sensor)
+        {
+            foreach(ThresholdSettings.PanelAndSensor panelAndSensor in auxSensors)
+            {
+                if(panelAndSensor.panel == Panel && panelAndSensor.sensor == sensor)
+                    return true;
+            }
+            return false;
+        }
+
+        private void LoadUIFromConfig(LoadFromConfigDelegateArgs args)
+        {
+            // Check the selected aux sensors.
+            List<ThresholdSettings.PanelAndSensor> auxSensors = ThresholdSettings.GetAuxSensors();
+            for(int sensor = 0; sensor < 4; ++sensor)
+                SensorSelectionButtons[sensor].IsChecked = IsSensorEnabled(auxSensors, sensor);
+        }
+    }
+
+    // This dialog sets which sensors are controlled by the auxilliary threshold.  The actual
+    // work is done by SensorSelector above.
+    public partial class SetAuxSensors: Window
+    {
+        public SetAuxSensors()
+        {
+            InitializeComponent();
+        }
+
+        private void OK_Click(object sender, RoutedEventArgs e)
+        {
+            Close();
+        }
+    }
+}