diff --git a/@MyAppColors/MyAppColors.m b/@MyAppColors/MyAppColors.m
index c615bc1..63d5a08 100644
--- a/@MyAppColors/MyAppColors.m
+++ b/@MyAppColors/MyAppColors.m
@@ -1,136 +1,140 @@
 % Set of colors indended to introduce some uniformity in GUIs
 
 classdef MyAppColors
 
     methods (Static)
         %% Predefined colors
         % Colors are represented by rgb triplets returned by static methods
         
         function rgb = warning()
             rgb = [0.93, 0.69, 0.13]; % Orange
         end
         
         function rgb = error()
             rgb = [1,0,0]; % Red
         end
         
         % Labview-style lamp indicator colors
         function rgb = lampOn()
             rgb = [0,1,0]; % Bright green
         end
         
         function rgb = lampOff()
             rgb = [0,0.4,0]; % Dark green
         end
         
         % Recolor app according to a new color scheme
         function applyScheme(Obj, scheme)
             persistent init_default default_main_color ...
                 default_label_text_color default_edit_text_color ...
                 default_edit_field_color default_axes_label_color
                     
             if ~exist('scheme', 'var')
                 scheme = 'default';
             end
 
             switch lower(scheme)
                 case 'dark'
                     main_color = [0,0.0,0.4];
                     label_text_color = [1,1,1];
                     edit_text_color = [0,0,0];
                     edit_field_color = [1,1,1];
                     axes_label_color = [0.9,0.9,1];
                 case 'bright'
                     main_color = [1,1,1];
                     label_text_color = [0,0,0.4];
                     edit_text_color = [0,0,0.];
                     edit_field_color = [1,1,1];
                     axes_label_color = [0,0,0];
                 case 'default'
                     if isempty(init_default)
                         
                         % Create invisible components and read their
                         % colors
                         Uf = uifigure('Visible', false);
                         Ef = uieditfield(Uf);
                         Lbl = uilabel(Uf);
                         Ax = axes(Uf);
                         
                         default_main_color = Uf.Color;
                         default_label_text_color = Lbl.FontColor;
                         default_edit_text_color = Ef.FontColor;
                         default_edit_field_color = Ef.BackgroundColor;
                         default_axes_label_color = Ax.XColor;
                         delete(Uf);
                         
                         init_default = false;
                     end
                     
                     main_color = default_main_color;
                     label_text_color = default_label_text_color;
                     edit_text_color = default_edit_text_color;
                     edit_field_color = default_edit_field_color;
                     axes_label_color = default_axes_label_color;
                 otherwise
                     error('Unknown scheme %s', scheme)
             end
 
             if isa(Obj, 'matlab.apps.AppBase')
                 Fig = findFigure(Obj);
                 MyAppColors.applyScheme(Fig, scheme);
                 return
             end
+            
+            if ~isprop(Obj, 'Type')
+                return
+            end
 
             switch Obj.Type
                 case 'figure'
                     Obj.Color = main_color;
                 case 'uitabgroup'
                     % Nothing to do
                 case 'uitab'
                     Obj.ForegroundColor = edit_text_color;
                     Obj.BackgroundColor = main_color;
                 case 'uibutton'
                     Obj.FontColor = label_text_color;
                     Obj.BackgroundColor = main_color;
                 case 'uistatebutton'
                     Obj.FontColor = label_text_color;
                     Obj.BackgroundColor = main_color;
                 case 'uidropdown'
                     Obj.FontColor = label_text_color;
                     Obj.BackgroundColor = main_color;
                 case 'uicheckbox'
                     Obj.FontColor = label_text_color;
                 case 'uieditfield'
                     Obj.FontColor = edit_text_color;
                     Obj.BackgroundColor = edit_field_color;
                 case 'uilabel'
                     Obj.FontColor = label_text_color;
                 case 'uilistbox'
                     Obj.FontColor = edit_text_color;
                     Obj.BackgroundColor = edit_field_color;
                 case 'uitextarea'
                     Obj.FontColor = edit_text_color;
                     Obj.BackgroundColor = edit_field_color;
                 case 'uipanel'
                     Obj.ForegroundColor = label_text_color;
                     Obj.BackgroundColor = main_color;
                 case 'axes'
                     Obj.BackgroundColor = main_color;
                     Obj.XColor = axes_label_color;
                     Obj.YColor = axes_label_color;
                     Obj.GridColor = [0.15, 0.15, 0.15];
                 case 'uimenu'
                     Obj.ForegroundColor = edit_text_color;
             end
 
             if isprop(Obj, 'Children')
 
                 % Recolor children
                 for i = 1:length(Obj.Children)
                     MyAppColors.applyScheme(Obj.Children(i), scheme);
                 end
             end
         end
     end
 end
 
diff --git a/Utility functions/isValidBaseVar.m b/Utility functions/isValidBaseVar.m
index c0d3e65..324f807 100644
--- a/Utility functions/isValidBaseVar.m	
+++ b/Utility functions/isValidBaseVar.m	
@@ -1,7 +1,9 @@
 % Check if the name belongs to a valid object in the global workspace
 
 function bool = isValidBaseVar(name)  
-    cmd = sprintf('exist(''%s'', ''var'') && isvalid(%s)', name, name);
+    cmd = sprintf(['exist(''%s'', ''var'') && ' ...
+        '((ismethod(%s, ''isvalid'') && isvalid(%s)) || ' ...
+        '~ismethod(%s, ''isvalid''))'], name, name, name, name);
     bool = evalin('base', cmd);
 end
 
diff --git a/Utility functions/runSingletonApp.m b/Utility functions/runSingletonApp.m
index 54d4a7b..fde652b 100644
--- a/Utility functions/runSingletonApp.m	
+++ b/Utility functions/runSingletonApp.m	
@@ -1,21 +1,36 @@
 function runSingletonApp(App, global_name)
     if isValidBaseVar(global_name)
         Fig = findFigure(App);
         close(Fig);
         
         % Make sure the new instance is deleted
         delete(App);
         App = evalin('base', global_name);
         
         % Bring to the focus the figure of existing app
         setFocus(App);
         
         error([global_name ' already exists']);
     else
         assignin('base', global_name, App);
         
         % Recolor app according to the present color scheme
         applyLocalColorScheme(App);
+        
+        % Set up a listener that will clear the global name 
+        addlistener(App, 'ObjectBeingDestroyed', @clearGlobalName);
+    end
+    
+    % The declaration of listener callback
+    function clearGlobalName(~, ~)
+        if ~isempty(global_name)
+            try
+                evalin('base', sprintf('clear(''%s'');', global_name));
+            catch ME
+                warning(['Could not clear global variable ''' ...
+                    global_name '''. Error: ' ME.message]);
+            end
+        end
     end
 end