diff --git a/EDSTest/DeviceInfoView.cs b/EDSTest/DeviceInfoView.cs
index 8bcbf2a6..3bcd435d 100644
--- a/EDSTest/DeviceInfoView.cs
+++ b/EDSTest/DeviceInfoView.cs
@@ -160,6 +160,8 @@ private void button_update_devfile_info_Click(object sender, EventArgs e)
                 //These are read only and auto calculated
                 //textBox_rxpdos.Text = eds.di.NrOfRXPDO.ToString();
                 //textBox_txpdos.Text = eds.di.NrOfTXPDO.ToString();
+
+                eds.dirty = true;
             }
             catch (Exception ex)
             {
diff --git a/EDSTest/DeviceODView.Designer.cs b/EDSTest/DeviceODView.Designer.cs
index 9e18fa8a..71027e2f 100644
--- a/EDSTest/DeviceODView.Designer.cs
+++ b/EDSTest/DeviceODView.Designer.cs
@@ -510,6 +510,7 @@ private void InitializeComponent()
             // 
             // comboBox_memory
             // 
+            this.comboBox_memory.DropDownStyle = System.Windows.Forms.ComboBoxStyle.DropDownList;
             this.comboBox_memory.FormattingEnabled = true;
             this.comboBox_memory.Location = new System.Drawing.Point(320, 219);
             this.comboBox_memory.Name = "comboBox_memory";
@@ -570,6 +571,7 @@ private void InitializeComponent()
             // 
             // comboBox_objecttype
             // 
+            this.comboBox_objecttype.DropDownStyle = System.Windows.Forms.ComboBoxStyle.DropDownList;
             this.comboBox_objecttype.Enabled = false;
             this.comboBox_objecttype.FormattingEnabled = true;
             this.comboBox_objecttype.Location = new System.Drawing.Point(108, 169);
@@ -588,6 +590,7 @@ private void InitializeComponent()
             // 
             // comboBox_datatype
             // 
+            this.comboBox_datatype.DropDownStyle = System.Windows.Forms.ComboBoxStyle.DropDownList;
             this.comboBox_datatype.FormattingEnabled = true;
             this.comboBox_datatype.Location = new System.Drawing.Point(108, 195);
             this.comboBox_datatype.Name = "comboBox_datatype";
@@ -623,6 +626,7 @@ private void InitializeComponent()
             // 
             // comboBox_accesstype
             // 
+            this.comboBox_accesstype.DropDownStyle = System.Windows.Forms.ComboBoxStyle.DropDownList;
             this.comboBox_accesstype.FormattingEnabled = true;
             this.comboBox_accesstype.Location = new System.Drawing.Point(108, 221);
             this.comboBox_accesstype.Name = "comboBox_accesstype";
@@ -656,6 +660,7 @@ private void InitializeComponent()
             // 
             // comboBox_pdomap
             // 
+            this.comboBox_pdomap.DropDownStyle = System.Windows.Forms.ComboBoxStyle.DropDownList;
             this.comboBox_pdomap.FormattingEnabled = true;
             this.comboBox_pdomap.Location = new System.Drawing.Point(108, 248);
             this.comboBox_pdomap.Name = "comboBox_pdomap";
diff --git a/EDSTest/DeviceODView.cs b/EDSTest/DeviceODView.cs
index c1f01f54..b9dcedd2 100644
--- a/EDSTest/DeviceODView.cs
+++ b/EDSTest/DeviceODView.cs
@@ -38,6 +38,7 @@ public partial class DeviceODView : MyTabUserControl
         public EDSsharp eds = null;
 
         ODentry selectedobject;
+        ODentry lastselectedobject;
         ListViewItem selecteditem;
         ListViewItem selecteditemsub;
 
@@ -45,22 +46,16 @@ public DeviceODView()
         {
             InitializeComponent();
 
-            comboBox_datatype.Items.Add("");
-
             foreach (DataType foo in Enum.GetValues(typeof(DataType)))
             {
                 comboBox_datatype.Items.Add(foo.ToString());
             }
 
-            comboBox_objecttype.Items.Add("");
-
             foreach (ObjectType foo in Enum.GetValues(typeof(ObjectType)))
             {
                 comboBox_objecttype.Items.Add(foo.ToString());
             }
 
-            comboBox_accesstype.Items.Add("");
-
             foreach (EDSsharp.AccessType foo in Enum.GetValues(typeof(EDSsharp.AccessType)))
             {
                 comboBox_accesstype.Items.Add(foo.ToString());
@@ -68,15 +63,11 @@ public DeviceODView()
 
             comboBox_accesstype.Items.Add("0x1003 rw/ro");
 
-
-            comboBox_memory.Items.Add("");
-
             foreach (StorageLocation foo in Enum.GetValues(typeof(StorageLocation)))
             {
                 comboBox_memory.Items.Add(foo.ToString());
             }
 
-            comboBox_pdomap.Items.Add("");
             comboBox_pdomap.Items.Add("no");
             comboBox_pdomap.Items.Add("optional");
 
@@ -85,14 +76,40 @@ public DeviceODView()
             listView_optional_objects.DoubleBuffering(true);
             listViewDetails.DoubleBuffering(true);
 
+            foreach(Control c in splitContainer4.Panel2.Controls)
+            {
+                if (c is CheckBox)
+                {
+                    ((CheckBox)c).CheckedChanged += DataDirty;
+                }
+                else
+                {
+                    c.TextChanged += DataDirty;
+                }
+            }
+        }
+
+        bool updating = false;
+
+        private void DataDirty(object sender, EventArgs e)
+        {
+            if (updating == true)
+                return;
+
+            button_save_changes.BackColor = Color.Red;
+
+
         }
 
-      
         private void button_save_changes_Click(object sender, EventArgs e)
         {
             if (selectedobject == null)
                 return;
 
+            eds.dirty = true;
+
+            button_save_changes.BackColor = default(Color);
+
             //Allow everything to be updated and control what is allowed via enable/disable for the control
 
             selectedobject.parameter_name = textBox_name.Text;
@@ -132,6 +149,7 @@ private void button_save_changes_Click(object sender, EventArgs e)
                 selectedobject.Disabled = !checkBox_enabled.Checked;
 
                 selectedobject.location = (StorageLocation)Enum.Parse(typeof(StorageLocation), comboBox_memory.SelectedItem.ToString());
+
             }
 
             if(selectedobject.parent == null && selectedobject.objecttype == ObjectType.ARRAY)
@@ -183,9 +201,15 @@ public void updatedetailslist()
         public void validateanddisplaydata()
         {
 
+
             if (selectedobject == null)
                 return;
 
+            lastselectedobject = selectedobject;
+
+            updating = true;
+
+
             ODentry od = (ODentry)selectedobject;
 
 
@@ -265,6 +289,7 @@ public void validateanddisplaydata()
                     textBox_defaultvalue.Enabled = false;
                 }
 
+                updating = false;
                 return; //nothing else to do at this point
             }
 
@@ -301,6 +326,8 @@ public void validateanddisplaydata()
 
             }
 
+            updating = false;
+
             return;
         }
 
@@ -412,6 +439,8 @@ private void listView_mandatory_objects_MouseClick(object sender, MouseEventArgs
 
             ListViewItem lvi = listView_mandatory_objects.SelectedItems[0];
 
+            if (checkdirty())
+                return;
 
             UInt16 idx = Convert.ToUInt16(lvi.Text, 16);
             updateselectedindexdisplay(idx);
@@ -429,6 +458,9 @@ private void list_mouseclick(ListView listview, MouseEventArgs e)
             if (listview.SelectedItems.Count == 0)
                 return;
 
+            if (checkdirty())
+                return;
+
             ListViewItem lvi = listview.SelectedItems[0];
             UInt16 idx = Convert.ToUInt16(lvi.Text, 16);
 
@@ -469,6 +501,8 @@ private void list_mouseclick(ListView listview, MouseEventArgs e)
 
         private void listView_MouseDown(ListView listview, MouseEventArgs e)
         {
+
+
             ListViewHitTestInfo HI = listview.HitTest(e.Location);
             if (e.Button == MouseButtons.Right)
             {
@@ -516,6 +550,9 @@ private void listViewDetails_MouseClick(object sender, MouseEventArgs e)
             if (listViewDetails.SelectedItems.Count == 0)
                 return;
 
+            if (checkdirty())
+                return;
+
             selecteditemsub = lvi;
 
             ODentry od = (ODentry)lvi.Tag;
@@ -645,6 +682,8 @@ private void addNewObjectToolStripMenuItem_Click(object sender, EventArgs e)
             if (ni.ShowDialog() == DialogResult.OK)
             {
 
+                eds.dirty = true;
+
                 ODentry od = new ODentry();
 
                 od.objecttype = ni.ot;
@@ -744,13 +783,15 @@ private void deleteObjectToolStripMenuItem_Click(object sender, EventArgs e)
                         }
                     }
 
+                  
 
                 }
             }
 
 
-                    if (MessageBox.Show(string.Format("Really delete index 0x{0:x4} ?", od.index), "Are you sure?", MessageBoxButtons.YesNo) == DialogResult.Yes)
+            if (MessageBox.Show(string.Format("Really delete index 0x{0:x4} ?", od.index), "Are you sure?", MessageBoxButtons.YesNo) == DialogResult.Yes)
             {
+                eds.dirty = true;
                 eds.ods.Remove(od.index);
                 populateindexlists();
             }
@@ -765,6 +806,7 @@ private void disableObjectToolStripMenuItem_Click(object sender, EventArgs e)
 
             ODentry od = (ODentry)item.Tag;
 
+            eds.dirty = true;
             od.Disabled = !od.Disabled;
             populateindexlists();
 
@@ -819,6 +861,7 @@ private void addSubItemToolStripMenuItem_Click(object sender, EventArgs e)
                     }
                 }
 
+                eds.dirty = true;
                 updateselectedindexdisplay(selectedobject.index);
                 validateanddisplaydata();
 
@@ -855,6 +898,7 @@ private void removeSubItemToolStripMenuItem_Click(object sender, EventArgs e)
 
                 od.parent.subobjects = newlist;
 
+                eds.dirty = true;
                 updateselectedindexdisplay(selectedobject.index);
                 validateanddisplaydata();
             }
@@ -930,12 +974,38 @@ private void listViewDetails_SelectedIndexChanged(object sender, EventArgs e)
             if (listViewDetails.SelectedItems.Count == 0)
                 return;
 
+            if (checkdirty())
+                return;
+
+
             ListViewItem lvi = listViewDetails.SelectedItems[0];
 
             selecteditemsub = lvi;
             selectedobject = (ODentry)lvi.Tag;
             validateanddisplaydata();
         }
+
+        private bool checkdirty()
+        {
+
+            if (button_save_changes.BackColor == Color.Red)
+            {
+                if (button_save_changes.BackColor == Color.Red)
+                {
+                    if (MessageBox.Show(String.Format("Unsaved changes on Index 0x{0:x4}/{1:x2}\nDo you wish to change objects and loose your changes", lastselectedobject.index, lastselectedobject.subindex), "Unsaved changes",MessageBoxButtons.YesNo) == DialogResult.No)
+                    {
+                        return true;
+                    }
+                    else
+                    {
+                        button_save_changes.BackColor = default(Color);
+                    }
+
+                }
+            }
+
+            return false;
+        }
     }
 
     public static class ControlExtensions
diff --git a/EDSTest/DevicePDOView.cs b/EDSTest/DevicePDOView.cs
index e5dce73f..a63d29b8 100644
--- a/EDSTest/DevicePDOView.cs
+++ b/EDSTest/DevicePDOView.cs
@@ -308,10 +308,10 @@ void updatePDOTXslot(ODentry od , int row)
 
         void listView_TXCOBmap_onComboBoxIndexChanged(int row, int col, string Text)
         {
-          
-            //row+0x1a00 will be the slot to adjust
 
+            //row+0x1a00 will be the slot to adjust
 
+            eds.dirty = true;
 
             UInt16 slot = (UInt16)(0x200 + Convert.ToUInt16(listView_TXCOBmap.Items[row].SubItems[1].Text, 16));
             ODentry slotod = eds.ods[slot];
@@ -486,6 +486,7 @@ private void button_addPDO_Click(object sender, EventArgs e)
 
             }
 
+            eds.dirty = true;
 
 
         }
@@ -506,7 +507,9 @@ private void button_deletePDO_Click(object sender, EventArgs e)
                     doUpdatePDOs();
                     doUpdateOD();
                 }
-                
+
+                eds.dirty = true;
+
             }
             catch (Exception ex)
             {
@@ -585,6 +588,8 @@ private void button_savepdochanges_Click(object sender, EventArgs e)
 
                 doUpdatePDOs();
                 doUpdateOD();
+
+                eds.dirty = true;
             }
             catch (Exception ex)
             {
diff --git a/EDSTest/Form1.Designer.cs b/EDSTest/Form1.Designer.cs
index bf5024b7..a7c8a47e 100644
--- a/EDSTest/Form1.Designer.cs
+++ b/EDSTest/Form1.Designer.cs
@@ -291,6 +291,7 @@ private void InitializeComponent()
             this.Icon = ((System.Drawing.Icon)(resources.GetObject("$this.Icon")));
             this.Name = "ODEditor_MainForm";
             this.Text = "Object Dictionary Editor v0.5";
+            this.FormClosing += new System.Windows.Forms.FormClosingEventHandler(this.ODEditor_MainForm_FormClosing);
             this.FormClosed += new System.Windows.Forms.FormClosedEventHandler(this.ODEditor_MainForm_FormClosed);
             this.Load += new System.EventHandler(this.ODEditor_MainForm_Load);
             this.menuStrip1.ResumeLayout(false);
diff --git a/EDSTest/Form1.cs b/EDSTest/Form1.cs
index a916dd84..401b407b 100644
--- a/EDSTest/Form1.cs
+++ b/EDSTest/Form1.cs
@@ -137,6 +137,8 @@ private void openEDSfile(string path)
 
                 DeviceView device = new DeviceView();
 
+                eds.onDataDirty += Eds_onDataDirty;
+
                 device.eds = eds;
                 tabControl1.TabPages.Add(eds.di.ProductName);
                 tabControl1.TabPages[tabControl1.TabPages.Count - 1].Controls.Add(device);
@@ -231,6 +233,8 @@ private void openXMLfile(string path)
 
                 DeviceView device = new DeviceView();
 
+                eds.onDataDirty += Eds_onDataDirty;
+
                 device.eds = eds;
                 tabControl1.TabPages[tabControl1.TabPages.Count - 1].Controls.Add(device);
                 device.Dock = DockStyle.Fill;
@@ -253,6 +257,30 @@ private void openXMLfile(string path)
 
         }
 
+        private void Eds_onDataDirty(bool dirty, EDSsharp sender)
+        {
+            foreach(TabPage page in tabControl1.TabPages)
+            {
+                foreach(Control c in page.Controls)
+                {
+                    if(c.GetType() == typeof(DeviceView))
+                    {
+                        DeviceView d = (DeviceView)c;
+                        if (d.eds.dirty == true)
+                        {
+                            page.BackColor = Color.Red;
+                        }
+                        else
+                        {
+                            page.BackColor = default(Color);
+                        }
+                    }
+
+                }
+
+            }
+
+        }
 
         private void tabControl1_DrawItem(Object sender, System.Windows.Forms.DrawItemEventArgs e)
         {
@@ -295,6 +323,13 @@ private void closeFileToolStripMenuItem_Click(object sender, EventArgs e)
                 // tabControl1.TabPages[tabControl1.TabPages.Count - 1].Controls.Add(device);
 
                 DeviceView device = (DeviceView)tabControl1.SelectedTab.Controls[0];
+
+                if(device.eds.dirty==true)
+                {
+                    if (MessageBox.Show( "All usaved changes will be lost\n continue?", "Unsaved changes", MessageBoxButtons.YesNo) == DialogResult.No)
+                        return;
+                }
+
                 network.Remove(device.eds);
 
                 tabControl1.TabPages.Remove(tabControl1.SelectedTab);
@@ -304,7 +339,7 @@ private void closeFileToolStripMenuItem_Click(object sender, EventArgs e)
 
         private void quitToolStripMenuItem_Click(object sender, EventArgs e)
         {
-            Close();
+             Close();
         }
 
         private void saveEDSToolStripMenuItem_Click(object sender, EventArgs e)
@@ -352,6 +387,8 @@ private void saveProjectXMLToolStripMenuItem_Click(object sender, EventArgs e)
                         coxml.dev = d;
 
                         coxml.writeXML(sfd.FileName);
+
+                        dv.eds.dirty = false;
     
                     }
 
@@ -368,6 +405,8 @@ private void newToolStripMenuItem_Click(object sender, EventArgs e)
             DeviceView device = new DeviceView();
 
             device.eds = eds;
+            eds.onDataDirty += Eds_onDataDirty;
+
             tabControl1.TabPages[tabControl1.TabPages.Count - 1].Controls.Add(device);
             device.Dock = DockStyle.Fill;
 
@@ -543,6 +582,7 @@ private void openNetworkfile(string file)
                 device.Dock = DockStyle.Fill;
 
                 network.Add(eds);
+                eds.onDataDirty += Eds_onDataDirty;
 
                 device.dispatch_updateOD();
 
@@ -656,6 +696,32 @@ private void saveExportAllToolStripMenuItem_Click(object sender, EventArgs e)
 
 
 
+            }
+        }
+
+        private void ODEditor_MainForm_FormClosing(object sender, FormClosingEventArgs e)
+        {
+
+            foreach (TabPage page in tabControl1.TabPages)
+            {
+                foreach (Control c in page.Controls)
+                {
+                    if (c.GetType() == typeof(DeviceView))
+                    {
+                        DeviceView d = (DeviceView)c;
+                        if (d.eds.dirty == true)
+                        {
+                           if(MessageBox.Show("Warning you have unsaved changes\n Do you wish to continue","Unsaved changes",MessageBoxButtons.YesNo)==DialogResult.No)
+                            {
+                                e.Cancel = true;
+                                return;
+                            }
+                        }
+                       
+                    }
+
+                }
+
             }
         }
     }
diff --git a/EDSTest/ListViewEx.cs b/EDSTest/ListViewEx.cs
index 719536a4..9037d3f0 100644
--- a/EDSTest/ListViewEx.cs
+++ b/EDSTest/ListViewEx.cs
@@ -346,7 +346,9 @@ private void ShowComboBox(Point location, Size sz, StringCollection data)
                     combo.Items.Add(text);
                 }
                 // Set the current text, take it from the current listview cell
+                noevent = true;
                 combo.Text = this.Items[row].SubItems[col].Text;
+                noevent = false;
                 // Calculate and set drop down width
                 combo.DropDownWidth = this.GetDropDownWidth(data);
                 // Show the combo
@@ -596,6 +598,8 @@ private void textBox_Leave(object sender, EventArgs e)
         /// </summary>
         /// <param name="sender"></param>
         /// <param name="e"></param>
+        /// 
+        bool noevent = false;
         private void combo_SelectedIndexChanged(object sender, EventArgs e)
         {
             try
@@ -605,7 +609,7 @@ private void combo_SelectedIndexChanged(object sender, EventArgs e)
                     this.Items[row].SubItems[col].Text = this.combo.Text;
                     this.combo.Visible = !this.hideComboAfterSelChange;
 
-                    if (onComboBoxIndexChanged != null)
+                    if (noevent==false && onComboBoxIndexChanged != null)
                         onComboBoxIndexChanged(row, col, combo.Text);
                 }
             }
diff --git a/libEDSsharp/Bridge.cs b/libEDSsharp/Bridge.cs
index 9c3cd856..8bdeb35c 100644
--- a/libEDSsharp/Bridge.cs
+++ b/libEDSsharp/Bridge.cs
@@ -23,6 +23,7 @@ You should have received a copy of the GNU General Public License
 using System.Text;
 using System.Threading.Tasks;
 using Xml2CSharp;
+using System.Text.RegularExpressions;
 
 /* I know i'm going to regret this
  * 
@@ -215,7 +216,10 @@ public EDSsharp convert(Device dev)
                 if (coo.AccessType != null)
                 {
                     string at = coo.AccessType;
-                    at = at.Replace("cons", "const"); // predicted regression from #23 
+
+                    Regex reg = new Regex(@"^cons$");
+                    at = reg.Replace(at,"const");
+
                     entry.accesstype = (EDSsharp.AccessType)Enum.Parse(typeof(EDSsharp.AccessType), at);
                 }
 
diff --git a/libEDSsharp/eds.cs b/libEDSsharp/eds.cs
index 1d55f9ba..06850f31 100644
--- a/libEDSsharp/eds.cs
+++ b/libEDSsharp/eds.cs
@@ -961,6 +961,23 @@ public enum AccessType
         public string edsfilename = null;
         public string xmlfilename = null;
 
+        //property to indicate unsaved data;
+        private bool _dirty;
+        public bool dirty
+        {
+            get
+            {
+                return _dirty;
+            }
+            set
+            {
+                _dirty = value;
+                if (onDataDirty != null)
+                    onDataDirty(_dirty,this);
+
+            }
+        }
+
         Dictionary<string, Dictionary<string, string>> eds;
         public SortedDictionary<UInt16, ODentry> ods;
         public SortedDictionary<UInt16, ODentry> dummy_ods;
@@ -975,11 +992,13 @@ public enum AccessType
 
         public UInt16 NodeId = 0;
 
-
+        public delegate void DataDirty(bool dirty, EDSsharp sender);
+        public event DataDirty onDataDirty;
 
         public EDSsharp()
         {
 
+
             eds = new Dictionary<string, Dictionary<string, string>>();
             ods = new SortedDictionary<UInt16, ODentry>();
             dummy_ods = new SortedDictionary<UInt16, ODentry>();
@@ -1023,6 +1042,11 @@ public EDSsharp()
 
         }
 
+        public void setdirty()
+        {
+
+        }
+
         string sectionname = "";
 
         public void parseline(string linex)