Index: Core/Common/src/Core.Common.Gui/Forms/MainWindow/MainWindow.xaml.cs
===================================================================
diff -u -r00bf02e3c099d01fbdb84735d8fc64de0fb98aaa -r0ea17b610f66d122fd9f0c8ef9db30740be455d8
--- Core/Common/src/Core.Common.Gui/Forms/MainWindow/MainWindow.xaml.cs	(.../MainWindow.xaml.cs)	(revision 00bf02e3c099d01fbdb84735d8fc64de0fb98aaa)
+++ Core/Common/src/Core.Common.Gui/Forms/MainWindow/MainWindow.xaml.cs	(.../MainWindow.xaml.cs)	(revision 0ea17b610f66d122fd9f0c8ef9db30740be455d8)
@@ -1008,21 +1008,13 @@
 
         private void OnFileOptionsClicked(object sender, RoutedEventArgs e)
         {
-            var optionsDialog = new OptionsDialog
+            var optionsDialog = new OptionsDialog(Gui.UserSettings);
+            if (optionsDialog.ShowDialog() == System.Windows.Forms.DialogResult.OK)
             {
-                UserSettings = Gui.UserSettings,
-                ColorTheme = (ColorTheme) Gui.UserSettings["colorTheme"],
-                OnAcceptChanges = ApplyColorTheme
-            };
-
-            optionsDialog.ShowDialog();
+                SetColorTheme((ColorTheme) Gui.UserSettings["colorTheme"]);
+            }
         }
 
-        private void ApplyColorTheme(OptionsDialog dialog)
-        {
-            SetColorTheme(dialog.ColorTheme);
-        }
-
         private void SetColorTheme(ColorTheme colorTheme)
         {
             if (colorTheme == ColorTheme.Dark && !(DockingManager.Theme is ExpressionDarkTheme))
Index: Core/Common/src/Core.Common.Gui/Forms/Options/OptionsDialog.Designer.cs
===================================================================
diff -u -r700ba80f40cd595e5227ab8338beb2446fe3a829 -r0ea17b610f66d122fd9f0c8ef9db30740be455d8
--- Core/Common/src/Core.Common.Gui/Forms/Options/OptionsDialog.Designer.cs	(.../OptionsDialog.Designer.cs)	(revision 700ba80f40cd595e5227ab8338beb2446fe3a829)
+++ Core/Common/src/Core.Common.Gui/Forms/Options/OptionsDialog.Designer.cs	(.../OptionsDialog.Designer.cs)	(revision 0ea17b610f66d122fd9f0c8ef9db30740be455d8)
@@ -53,23 +53,21 @@
             this.buttonCancel.DialogResult = System.Windows.Forms.DialogResult.Cancel;
             this.buttonCancel.Name = "buttonCancel";
             this.buttonCancel.UseVisualStyleBackColor = true;
-            this.buttonCancel.Click += new System.EventHandler(this.buttonCancel_Click);
             // 
             // buttonOk
             // 
             resources.ApplyResources(this.buttonOk, "buttonOk");
             this.buttonOk.DialogResult = System.Windows.Forms.DialogResult.OK;
             this.buttonOk.Name = "buttonOk";
             this.buttonOk.UseVisualStyleBackColor = true;
-            this.buttonOk.Click += new System.EventHandler(this.buttonOk_Click);
+            this.buttonOk.Click += new System.EventHandler(this.ButtonOkClick);
             // 
             // comboBoxTheme
             // 
             this.comboBoxTheme.DropDownStyle = System.Windows.Forms.ComboBoxStyle.DropDownList;
             this.comboBoxTheme.FormattingEnabled = true;
             resources.ApplyResources(this.comboBoxTheme, "comboBoxTheme");
             this.comboBoxTheme.Name = "comboBoxTheme";
-            this.comboBoxTheme.SelectedIndexChanged += new System.EventHandler(this.comboBoxTheme_SelectedIndexChanged);
             // 
             // label1
             // 
Index: Core/Common/src/Core.Common.Gui/Forms/Options/OptionsDialog.cs
===================================================================
diff -u -r00bf02e3c099d01fbdb84735d8fc64de0fb98aaa -r0ea17b610f66d122fd9f0c8ef9db30740be455d8
--- Core/Common/src/Core.Common.Gui/Forms/Options/OptionsDialog.cs	(.../OptionsDialog.cs)	(revision 00bf02e3c099d01fbdb84735d8fc64de0fb98aaa)
+++ Core/Common/src/Core.Common.Gui/Forms/Options/OptionsDialog.cs	(.../OptionsDialog.cs)	(revision 0ea17b610f66d122fd9f0c8ef9db30740be455d8)
@@ -1,60 +1,22 @@
 using System;
 using System.Collections.ObjectModel;
 using System.Configuration;
-using System.Security.Permissions;
 using System.Windows.Forms;
 using Core.Common.Utils.Reflection;
 
 namespace Core.Common.Gui.Forms.Options
 {
     public partial class OptionsDialog : Form
     {
-        private ApplicationSettingsBase userSettings;
+        private readonly ApplicationSettingsBase userSettings;
 
-        public OptionsDialog()
+        public OptionsDialog(ApplicationSettingsBase userSettings)
         {
             InitializeComponent();
-            SetColorThemeOptions();
-        }
 
-        public ApplicationSettingsBase UserSettings
-        {
-            get
-            {
-                return userSettings;
-            }
-            set
-            {
-                UpdateUserSettings(value);
-            }
-        }
+            this.userSettings = userSettings;
 
-        public ColorTheme ColorTheme
-        {
-            get
-            {
-                return (ColorTheme) comboBoxTheme.SelectedValue;
-            }
-            set
-            {
-                comboBoxTheme.SelectedValue = value;
-            }
-        }
-
-        // TODO: Call this method
-        public Action<OptionsDialog> OnAcceptChanges { get; set; }
-
-        private void AcceptChanges()
-        {
-            SetValuesToSettings();
-            if (OnAcceptChanges != null)
-            {
-                OnAcceptChanges(this);
-            }
-        }
-
-        private void DeclineChanges()
-        {
+            SetColorThemeOptions();
             SetSettingsValuesToControls();
         }
 
@@ -74,38 +36,28 @@
             comboBoxTheme.DisplayMember = TypeUtils.GetMemberName<ColorThemeItem>(cti => cti.DisplayName);
         }
 
-        /// <summary>
-        /// Safe call because of linkdemand
-        /// </summary>
-        /// <param name="settings"></param>
-        [SecurityPermission(SecurityAction.LinkDemand, Flags = SecurityPermissionFlag.UnmanagedCode)]
-        private void UpdateUserSettings(ApplicationSettingsBase settings)
-        {
-            userSettings = settings;
-            SetSettingsValuesToControls();
-        }
-
-        /// <summary>
-        /// Dialog created.
-        /// </summary>
         private void SetSettingsValuesToControls()
         {
+            if (userSettings == null)
+            {
+                return;
+            }
+
             checkBoxStartPage.Checked = (bool) userSettings["showStartPage"];
+            comboBoxTheme.SelectedValue = (ColorTheme) userSettings["colorTheme"];
         }
 
-        /// <summary>
-        /// Ok clicked.
-        /// </summary>
-        private void SetValuesToSettings()
+        private void ButtonOkClick(object sender, EventArgs e)
         {
-            if ((bool) userSettings["showStartPage"] != checkBoxStartPage.Checked)
+            if (userSettings == null)
             {
-                userSettings["showStartPage"] = checkBoxStartPage.Checked;
+                return;
             }
+
+            userSettings["showStartPage"] = checkBoxStartPage.Checked;
+            userSettings["colorTheme"] = comboBoxTheme.SelectedValue;
         }
 
-        private void comboBoxTheme_SelectedIndexChanged(object sender, EventArgs e) {}
-
         /// <summary>
         /// Used for localizing the items in the theme selection combo box.
         /// </summary>
@@ -121,25 +73,5 @@
             /// </summary>
             public string DisplayName { get; set; }
         }
-
-        protected override void OnFormClosed(FormClosedEventArgs e)
-        {
-            if (DialogResult != DialogResult.OK)
-            {
-                DeclineChanges();
-            }
-
-            base.OnFormClosed(e);
-        }
-
-        private void buttonOk_Click(object sender, EventArgs e)
-        {
-            AcceptChanges();
-        }
-
-        private void buttonCancel_Click(object sender, EventArgs e)
-        {
-            DeclineChanges();
-        }
     }
 }
\ No newline at end of file
Index: Core/Common/test/Core.Common.Gui.Test/Forms/Options/OptionsDialogTest.cs
===================================================================
diff -u -r00bf02e3c099d01fbdb84735d8fc64de0fb98aaa -r0ea17b610f66d122fd9f0c8ef9db30740be455d8
--- Core/Common/test/Core.Common.Gui.Test/Forms/Options/OptionsDialogTest.cs	(.../OptionsDialogTest.cs)	(revision 00bf02e3c099d01fbdb84735d8fc64de0fb98aaa)
+++ Core/Common/test/Core.Common.Gui.Test/Forms/Options/OptionsDialogTest.cs	(.../OptionsDialogTest.cs)	(revision 0ea17b610f66d122fd9f0c8ef9db30740be455d8)
@@ -9,7 +9,7 @@
         [Test]
         public void GivenGeneralOptionsControlCreated_WhenRetrievingOptionsItems_ThenOptionsShouldBeTranslated()
         {
-            using (var control = new Gui.Forms.Options.OptionsDialog())
+            using (var control = new Gui.Forms.Options.OptionsDialog(null))
             {
                 var subControl = (ComboBox)control.Controls.Find("comboBoxTheme", true)[0];