Merge pull request #149 from ncarrillo/cairo-push-opacity

Implemented PushOpacity for Cairo

src/Gtk/Perspex.Cairo/Media/DrawingContext.cs

@@ -203,8 +203,12 @@ namespace Perspex.Cairo.Media
         /// <returns>A disposable used to undo the opacity.</returns>
         public IDisposable PushOpacity(double opacity)
         {
-            // TODO: Implement
-            return Disposable.Empty;
+            opacityOverride = opacity;
+
+            return Disposable.Create(() =>
+            {
+                opacityOverride = 1.0f;
+            });
         }
 
         /// <summary>

src/Gtk/Perspex.Cairo/Media/FormattedTextImpl.cs

@@ -30,7 +30,7 @@ namespace Perspex.Cairo.Media
             Layout.FontDescription = new Pango.FontDescription
             {
                 Family = fontFamily,
-                Size = Pango.Units.FromDouble(fontSize * 0.73),
+                Size = Pango.Units.FromDouble(fontSize),
                 Style = (Pango.Style)fontStyle,
                 Weight = fontWeight.ToCairo()
             };