support for .NET framework 3.5

Still have bugs

Net35/HandyControl_Net35/Data/Gif/GifFrameDimension.cs

@@ -0,0 +1,29 @@
+using System;
+
+namespace HandyControl.Data
+{
+    internal class GifFrameDimension
+    {
+        public GifFrameDimension(Guid guid) => Guid = guid;
+
+        public Guid Guid { get; }
+
+        public static GifFrameDimension Time { get; } = new GifFrameDimension(new Guid("{6aedbd6d-3fb5-418a-83a6-7f45229dc872}"));
+
+        public static GifFrameDimension Resolution { get; } = new GifFrameDimension(new Guid("{84236f7b-3bd3-428f-8dab-4ea1439ca315}"));
+
+        public static GifFrameDimension Page { get; } = new GifFrameDimension(new Guid("{7462dc86-6180-4c7e-8e3f-ee7333a7a483}"));
+
+        public override bool Equals(object o) => o is GifFrameDimension format && Guid == format.Guid;
+
+        public override int GetHashCode() => Guid.GetHashCode();
+
+        public override string ToString()
+        {
+            if (Equals(this, Time)) return "Time";
+            if (Equals(this, Resolution)) return "Resolution";
+            if (Equals(this, Page)) return "Page";
+            return "[FrameDimension: " + Guid + "]";
+        }
+    }
+}