A bit of refactoring to be able to find some issue...

GreenshotPlugin/UnmanagedHelpers/Structs/POINT.cs

@@ -0,0 +1,37 @@
+using System;
+using System.Drawing;
+using System.Runtime.InteropServices;
+
+namespace GreenshotPlugin.UnmanagedHelpers.Structs
+{
+    [StructLayout(LayoutKind.Sequential), Serializable()]
+    public struct POINT {
+        public int X;
+        public int Y;
+
+        public POINT(int x, int y) {
+            X = x;
+            Y = y;
+        }
+        public POINT(Point point) {
+            X = point.X;
+            Y = point.Y;
+        }
+
+        public static implicit operator Point(POINT p) {
+            return new Point(p.X, p.Y);
+        }
+
+        public static implicit operator POINT(Point p) {
+            return new POINT(p.X, p.Y);
+        }
+
+        public Point ToPoint() {
+            return new Point(X, Y);
+        }
+
+        public override string ToString() {
+            return X + "," + Y;
+        }
+    }
+}