Calculated the correct font size for use in WPF.

src/toolkit/Community.VisualStudio.Toolkit.Shared/FontsAndColors/BaseFontAndColorCategory.cs

@@ -246,7 +246,7 @@ int IVsFontAndColorEvents.OnFontChanged(ref Guid rguidCategory, FontInfo[] pInfo
             // only want to handle the changes for this category.
             if (rguidCategory.Equals(_categoryGuid))
             {
-                EmitChange((x) => x.SetFont(ref pInfo[0]));
+                EmitChange((x) => x.SetFont(ref pLOGFONT[0], ref pInfo[0]));
             }
             return VSConstants.S_OK;
         }

src/toolkit/Community.VisualStudio.Toolkit.Shared/FontsAndColors/ConfiguredFont.cs

@@ -1,4 +1,5 @@
-using System.ComponentModel;
+using System;
+using System.ComponentModel;
 using System.Windows.Media;
 using Microsoft.VisualStudio.PlatformUI;
 using Microsoft.VisualStudio.Shell.Interop;
@@ -22,14 +23,16 @@ public class ConfiguredFont : ObservableObject
         private FontFamily? _family;
         private bool _hasFamily;
         private string _familyName;
+        private int _pointSize;
         private double _size;
         private byte _characterSet;
 
-        internal ConfiguredFont(ref FontInfo info)
+        internal ConfiguredFont(ref LOGFONTW logfont, ref FontInfo fontInfo)
         {
-            _familyName = info.bstrFaceName;
-            _size = info.wPointSize;
-            _characterSet = info.iCharSet;
+            _familyName = fontInfo.bstrFaceName;
+            _pointSize = fontInfo.wPointSize;
+            _size = CalculateFontSize(ref logfont);
+            _characterSet = fontInfo.iCharSet;
         }
 
         /// <summary>
@@ -61,7 +64,14 @@ public FontFamily? Family
         public string FamilyName => _familyName;
 
         /// <summary>
-        /// The font size.
+        /// The font size, in points. This is the value specified on the <i>Fonts and Colors</i> options page.
+        /// </summary>
+        public int PointSize => _pointSize;
+
+        /// <summary>
+        /// The font size, for use in WPF. This is the font size that can be used in WPF controls.
+        /// For example, the value can be used directly in the 
+        /// <see cref="System.Windows.Documents.TextElement.FontSize"/> property.
         /// </summary>
         public double Size => _size;
 
@@ -70,17 +80,19 @@ public FontFamily? Family
         /// </summary>
         public byte CharacterSet => _characterSet;
 
-        internal bool Update(ref FontInfo info)
+        internal bool Update(ref LOGFONTW logfont, ref FontInfo info)
         {
             bool changed = false;
             string oldFaceName = _familyName;
+            int oldPointSize = _pointSize;
             double oldSize = _size;
             byte oldCharacterSet = _characterSet;
 
             // Update all of the fields first so that
             // everything is set before we raise the events.
             _familyName = info.bstrFaceName;
-            _size = info.wPointSize;
+            _pointSize = info.wPointSize;
+            _size = CalculateFontSize(ref logfont);
             _characterSet = info.iCharSet;
 
             if (!string.Equals(oldFaceName, _familyName))
@@ -92,6 +104,12 @@ internal bool Update(ref FontInfo info)
                 NotifyPropertyChanged(nameof(FamilyName));
             }
 
+            if (oldPointSize != _pointSize)
+            {
+                changed = true;
+                NotifyPropertyChanged(nameof(PointSize));
+            }
+
             if (oldSize != _size)
             {
                 changed = true;
@@ -106,5 +124,18 @@ internal bool Update(ref FontInfo info)
 
             return changed;
         }
+
+        private static double CalculateFontSize(ref LOGFONTW logfont)
+        {
+            return Math.Abs(logfont.lfHeight) * 96.0 /
+#if VS14
+                // `DpiAwareness` does not exist in VS 14, so default
+                // to 96.0, which is the standard system DPI.
+                96.0
+#else
+                Microsoft.VisualStudio.Utilities.DpiAwareness.SystemDpiY
+#endif
+                ;
+        }
     }
 }

src/toolkit/Community.VisualStudio.Toolkit.Shared/FontsAndColors/ConfiguredFontAndColorSet.cs

@@ -14,13 +14,14 @@ namespace Community.VisualStudio.Toolkit
 
         internal ConfiguredFontAndColorSet(
             T category,
-            ref FontInfo font,
+            ref LOGFONTW logfont,
+            ref FontInfo fontInfo,
             Dictionary<ColorDefinition, ConfiguredColor> colors,
             Action<IFontAndColorChangeListener> onDispose
         )
         {
             Category = category;
-            Font = new ConfiguredFont(ref font);
+            Font = new ConfiguredFont(ref logfont, ref fontInfo);
             _colors = colors;
             _onDispose = onDispose;
         }
@@ -64,9 +65,9 @@ public ConfiguredColor GetColor(ColorDefinition definition)
         /// </summary>
         public event EventHandler<ConfiguredColorChangedEventArgs>? ColorChanged;
 
-        void IFontAndColorChangeListener.SetFont(ref FontInfo info)
+        void IFontAndColorChangeListener.SetFont(ref LOGFONTW logfont, ref FontInfo info)
         {
-            if (Font.Update(ref info))
+            if (Font.Update(ref logfont, ref info))
             {
                 FontChanged?.Invoke(this, EventArgs.Empty);
             }

src/toolkit/Community.VisualStudio.Toolkit.Shared/FontsAndColors/FontsAndColors.cs

@@ -37,10 +37,12 @@ internal FontsAndColors()
                 T category = BaseFontAndColorCategory<T>.Instance;
 
                 FontInfo[] fontInfo = new FontInfo[1];
-                ErrorHandler.ThrowOnFailure(storage.GetFont(null, fontInfo));
+                LOGFONTW[] logfont = new LOGFONTW[1];
+                ErrorHandler.ThrowOnFailure(storage.GetFont(logfont, fontInfo));
 
                 ConfiguredFontAndColorSet<T> set = new(
                     category,
+                    ref logfont[0],
                     ref fontInfo[0],
                     await GetColorsAsync(category, categoryGuid, storage),
                     category.UnregisterChangeListener

src/toolkit/Community.VisualStudio.Toolkit.Shared/FontsAndColors/IFontAndColorChangeListener.cs

@@ -4,7 +4,7 @@ namespace Community.VisualStudio.Toolkit
 {
     internal interface IFontAndColorChangeListener
     {
-        void SetFont(ref FontInfo info);
+        void SetFont(ref LOGFONTW logfont, ref FontInfo info);
 
         void SetColor(ColorDefinition definition, uint background, uint foreground, FontStyle fontStyle);
     }