Index: Core/Plugins/src/Core.Plugins.CommonTools.Gui/Commands/Charting/ChartViewCommandBase.cs
===================================================================
diff -u -rfefc0cc505a41a79d4643c80335484daf4ca30ce -ra4ab963c024ed8783e21f8fd4b490322f414ea02
--- Core/Plugins/src/Core.Plugins.CommonTools.Gui/Commands/Charting/ChartViewCommandBase.cs	(.../ChartViewCommandBase.cs)	(revision fefc0cc505a41a79d4643c80335484daf4ca30ce)
+++ Core/Plugins/src/Core.Plugins.CommonTools.Gui/Commands/Charting/ChartViewCommandBase.cs	(.../ChartViewCommandBase.cs)	(revision a4ab963c024ed8783e21f8fd4b490322f414ea02)
@@ -1,9 +1,14 @@
-using System.Drawing;
+using System;
+using System.Drawing;
 using Core.Common.Controls.Swf.Charting;
 using Core.Common.Gui;
 
 namespace Core.Plugins.CommonTools.Gui.Commands.Charting
 {
+    /// <summary>
+    /// Classes derived from this class will have a possibility to obtain the active
+    /// <see cref="ChartView"/> (if any) and the <see cref="IGui"/>.
+    /// </summary>
     public abstract class ChartViewCommandBase : GuiCommand
     {
         public override bool Enabled
@@ -22,6 +27,10 @@
             }
         }
 
+        /// <summary>
+        /// Gets the currently active view if it is a <see cref="ChartView"/> and
+        /// <c>null</c> otherwise.
+        /// </summary>
         protected ChartView View
         {
             get
@@ -32,9 +41,16 @@
             }
         }
 
-        protected Font GetChangedFontSize(Font font, int pixels)
+        /// <summary>
+        /// Changes the size of the <paramref name="font"/> with <paramref name="points"/> points.
+        /// </summary>
+        /// <param name="font">The <see cref="Font"/> to modify the size of.</param>
+        /// <param name="points">The change in points to modify the size of <paramref name="font"/> by.</param>
+        /// <returns>A new instance of <see cref="Font"/> with the new size.</returns>
+        /// <exception cref="ArgumentException">Thrown when modification ends up in a font size &lt;= 0.</exception>
+        protected Font GetChangedFontSize(Font font, int points)
         {
-            return new Font(font.FontFamily, font.Size + pixels, font.Style);
+            return new Font(font.FontFamily, font.SizeInPoints + points, font.Style);
         }
     }
 }
\ No newline at end of file
Index: Core/Plugins/test/Core.Plugins.CommonTools.Gui.Test/Commands/Charting/ChartViewCommandBaseTest.cs
===================================================================
diff -u
--- Core/Plugins/test/Core.Plugins.CommonTools.Gui.Test/Commands/Charting/ChartViewCommandBaseTest.cs	(revision 0)
+++ Core/Plugins/test/Core.Plugins.CommonTools.Gui.Test/Commands/Charting/ChartViewCommandBaseTest.cs	(revision a4ab963c024ed8783e21f8fd4b490322f414ea02)
@@ -0,0 +1,190 @@
+using System;
+using System.Drawing;
+using Core.Common.Controls.Swf.Charting;
+using Core.Common.Gui;
+using Core.Common.Test.TestObjects;
+using Core.Plugins.CommonTools.Gui.Commands.Charting;
+using NUnit.Framework;
+using Rhino.Mocks;
+
+namespace Core.Plugins.CommonTools.Gui.Test.Commands.Charting
+{
+    [TestFixture]
+    public class ChartViewCommandBaseTest
+    {
+        private MockRepository mocks;
+
+        [SetUp]
+        public void SetUp()
+        {
+            mocks = new MockRepository();
+        }
+
+        [Test]
+        [TestCase(11)]
+        [TestCase(1)]
+        [TestCase(0)]
+        [TestCase(-11)]
+        [TestCase(-5)]
+        public void GetChangedFontSize_StartWithSize12ModifiedWithPoints_ReturnsSmallerFont(int points)
+        {
+            // Setup
+            var command = new TestChartViewCommandBase();
+            var startSize = 12f;
+            var font = new Font(FontFamily.GenericSansSerif, startSize);
+
+            // Call
+            var newFont = command.GetChangedFontSize(font, points);
+
+            // Assert
+            Assert.AreEqual(startSize + points, newFont.SizeInPoints);
+        }
+
+        [Test]
+        [TestCase(-12)]
+        [TestCase(-13)]
+        public void GetChangedFontSize_StartWithSize12ModifiedWithPointsLargerEqualTo12_ThrowsArgumentException(int points)
+        {
+            // Setup
+            var command = new TestChartViewCommandBase();
+            var startSize = 12f;
+            var font = new Font(FontFamily.GenericSansSerif, startSize);
+
+            // Call
+            TestDelegate test = () => command.GetChangedFontSize(font, points);
+
+            // Assert
+            Assert.Throws<ArgumentException>(test);
+        }
+
+        [Test]
+        public void View_WithoutGui_Null()
+        {
+            // Setup
+            var command = new TestChartViewCommandBase();
+
+            // Call
+            var result = command.GetView();
+
+            // Assert
+            Assert.IsNull(result);
+        }
+
+        [Test]
+        public void View_GuiWithoutDocumentView_ThrowsNullReferenceException()
+        {
+            // Setup
+            var guiMock = mocks.StrictMock<IGui>();
+            guiMock.Expect(g => g.DocumentViews).Return(null);
+
+            mocks.ReplayAll();
+
+            var command = new TestChartViewCommandBase
+            {
+                Gui = guiMock
+            };
+
+            // Call
+            TestDelegate test = () => command.GetView();
+
+            // Assert
+            Assert.Throws<NullReferenceException>(test);
+
+            mocks.VerifyAll();
+        }
+
+        [Test]
+        public void View_GuiWithDocumentViewActiveViewNull_CallsActiveViewReturnsNull()
+        {
+            // Setup
+            var guiMock = mocks.StrictMock<IGui>();
+            var viewListMock = mocks.StrictMock<IViewList>();
+            guiMock.Expect(g => g.DocumentViews).Return(viewListMock);
+            viewListMock.Expect(vl => vl.ActiveView).Return(null);
+
+            mocks.ReplayAll();
+
+            var command = new TestChartViewCommandBase
+            {
+                Gui = guiMock
+            };
+
+            // Call
+            var result = command.GetView();
+
+            // Assert
+            Assert.IsNull(result);
+
+            mocks.VerifyAll();
+        }
+
+        [Test]
+        public void View_GuiWithDocumentViewActiveViewNotChartView_CallsActiveViewReturnsNull()
+        {
+            // Setup
+            var guiMock = mocks.StrictMock<IGui>();
+            var viewListMock = mocks.StrictMock<IViewList>();
+            guiMock.Expect(g => g.DocumentViews).Return(viewListMock);
+            viewListMock.Expect(vl => vl.ActiveView).Return(new TestView());
+
+            mocks.ReplayAll();
+
+            var command = new TestChartViewCommandBase
+            {
+                Gui = guiMock
+            };
+
+            // Call
+            var result = command.GetView();
+
+            // Assert
+            Assert.IsNull(result);
+
+            mocks.VerifyAll();
+        }
+
+        [Test]
+        public void View_GuiWithDocumentViewActiveViewChartView_CallsActiveViewReturnsChartView()
+        {
+            // Setup
+            var expectedView = new ChartView();
+
+            var guiMock = mocks.StrictMock<IGui>();
+            var viewListMock = mocks.StrictMock<IViewList>();
+            guiMock.Expect(g => g.DocumentViews).Return(viewListMock);
+            viewListMock.Expect(vl => vl.ActiveView).Return(expectedView);
+
+            mocks.ReplayAll();
+
+            var command = new TestChartViewCommandBase
+            {
+                Gui = guiMock
+            };
+
+            // Call
+            var result = command.GetView();
+
+            // Assert
+            Assert.AreSame(expectedView, result);
+
+            mocks.VerifyAll();
+        }
+
+        private class TestChartViewCommandBase : ChartViewCommandBase {
+            public override void Execute(params object[] arguments)
+            {
+                throw new NotImplementedException();
+            }
+
+            public new Font GetChangedFontSize(Font font, int points)
+            {
+                return base.GetChangedFontSize(font, points);
+            }
+
+            public ChartView GetView()
+            {
+                return View;
+            }
+        } 
+    }
+}
\ No newline at end of file
Index: Core/Plugins/test/Core.Plugins.CommonTools.Gui.Test/Core.Plugins.CommonTools.Gui.Test.csproj
===================================================================
diff -u -r10671f81a86637fcab2f4a38af58a9899ca1b240 -ra4ab963c024ed8783e21f8fd4b490322f414ea02
--- Core/Plugins/test/Core.Plugins.CommonTools.Gui.Test/Core.Plugins.CommonTools.Gui.Test.csproj	(.../Core.Plugins.CommonTools.Gui.Test.csproj)	(revision 10671f81a86637fcab2f4a38af58a9899ca1b240)
+++ Core/Plugins/test/Core.Plugins.CommonTools.Gui.Test/Core.Plugins.CommonTools.Gui.Test.csproj	(.../Core.Plugins.CommonTools.Gui.Test.csproj)	(revision a4ab963c024ed8783e21f8fd4b490322f414ea02)
@@ -76,6 +76,7 @@
     <Reference Include="System.Xml" />
   </ItemGroup>
   <ItemGroup>
+    <Compile Include="Commands\Charting\ChartViewCommandBaseTest.cs" />
     <Compile Include="Forms\Charting\ChartTreeNodePresenterTest.cs" />
     <Compile Include="TestViewList.cs" />
     <Compile Include="Properties\AssemblyInfo.cs" />
@@ -94,6 +95,14 @@
       <Project>{F49BD8B2-332A-4C91-A196-8CCE0A2C7D98}</Project>
       <Name>Core.Common.Utils</Name>
     </ProjectReference>
+    <ProjectReference Include="..\..\..\Common\test\Core.Common.TestUtil\Core.Common.TestUtil.csproj">
+      <Project>{D749EE4C-CE50-4C17-BF01-9A953028C126}</Project>
+      <Name>Core.Common.TestUtil</Name>
+    </ProjectReference>
+    <ProjectReference Include="..\..\..\Common\test\Core.Common.Test\Core.Common.Test.csproj">
+      <Project>{E0990383-FB2E-47D1-99CD-9B9FA2929E5B}</Project>
+      <Name>Core.Common.Test</Name>
+    </ProjectReference>
     <ProjectReference Include="..\..\..\Plugins\src\Core.Plugins.CommonTools.Gui\Core.Plugins.CommonTools.Gui.csproj">
       <Project>{93E73FAB-FAE8-49C6-9ABB-27D24DF761F6}</Project>
       <Name>Core.Plugins.CommonTools.Gui</Name>