diff --git a/WelsonJS.Toolkit/WelsonJS.Toolkit/Toolkit.cs b/WelsonJS.Toolkit/WelsonJS.Toolkit/Toolkit.cs
index 6888f99..5e6de61 100644
--- a/WelsonJS.Toolkit/WelsonJS.Toolkit/Toolkit.cs
+++ b/WelsonJS.Toolkit/WelsonJS.Toolkit/Toolkit.cs
@@ -14,6 +14,7 @@
  *         - https://stackoverflow.com/questions/13547639/return-window-handle-by-its-name-title
  *         - https://blog.naver.com/zlatmgpdjtiq/222016292758
  *         - https://stackoverflow.com/questions/5427020/prompt-dialog-in-windows-forms
+ *         - https://stackoverflow.com/questions/60203135/set-delta-in-a-wm-mousewheel-message-to-send-with-postmessage
  */
 
 using System;
@@ -56,6 +57,32 @@ namespace WelsonJS
             WM_CHAR = 0x102,     //char
             WM_COMMAND = 0x111
         }
+        public enum WinMsgMouseKey : int
+        {
+            MK_NONE = 0x0000,
+            MK_LBUTTON = 0x0001,
+            MK_RBUTTON = 0x0002,
+            MK_SHIFT = 0x0004,
+            MK_CONTROL = 0x0008,
+            MK_MBUTTON = 0x0010,
+            MK_XBUTTON1 = 0x0020,
+            MK_XBUTTON2 = 0x0040
+        }
+
+        public int directionUp = 1;
+        public int directionDown = -1;
+        public const uint WM_MOUSEWHEEL = 0x020A;
+
+        public IntPtr MAKEWPARAM(int direction, float multiplier, WinMsgMouseKey button)
+        {
+            int delta = (int)(SystemInformation.MouseWheelScrollDelta * multiplier);
+            return (IntPtr)(((delta << 16) * Math.Sign(direction) | (ushort)button));
+        }
+
+        public IntPtr MAKELPARAM(int low, int high)
+        {
+            return (IntPtr)((high << 16) | (low & 0xFFFF));
+        }
 
         public IntPtr QueryHandleWindow(string wName)
         {
@@ -137,5 +164,39 @@ namespace WelsonJS
             string result = WelsonJS.Prompt.ShowDialog(message, ApplicationName);
             return (result == "" ? _default : result);
         }
+
+        [ComVisible(true)]
+        public bool MouseWheelDown(string wName)
+        {
+            bool result = false;
+
+            IntPtr hWnd = QueryHandleWindow(wName);
+            if (hWnd != IntPtr.Zero)
+            {
+                // Scrolls [Handle] down by 1/2 wheel rotation with Left Button pressed
+                IntPtr wParam = MAKEWPARAM(directionDown, .5f, WinMsgMouseKey.MK_LBUTTON);
+                IntPtr lParam = MAKELPARAM(Cursor.Position.X, Cursor.Position.Y);
+                result = PostMessage(hWnd, WM_MOUSEWHEEL, (int)wParam, lParam);
+            }
+
+            return result;
+        }
+
+        [ComVisible(true)]
+        public bool MouseWheelUp(string wName)
+        {
+            bool result = false;
+
+            IntPtr hWnd = QueryHandleWindow(wName);
+            if (hWnd != IntPtr.Zero)
+            {
+                // Scrolls [Handle] up by 1/2 wheel rotation with Left Button pressed
+                IntPtr wParam = MAKEWPARAM(directionUp, .5f, WinMsgMouseKey.MK_LBUTTON);
+                IntPtr lParam = MAKELPARAM(Cursor.Position.X, Cursor.Position.Y);
+                result = PostMessage(hWnd, WM_MOUSEWHEEL, (int)wParam, lParam);
+            }
+
+            return result;
+        }
     }
 }
diff --git a/WelsonJS.Toolkit/WelsonJS.Toolkit/WelsonJS.Toolkit.csproj b/WelsonJS.Toolkit/WelsonJS.Toolkit/WelsonJS.Toolkit.csproj
index 2748e95..9c69927 100644
--- a/WelsonJS.Toolkit/WelsonJS.Toolkit/WelsonJS.Toolkit.csproj
+++ b/WelsonJS.Toolkit/WelsonJS.Toolkit/WelsonJS.Toolkit.csproj
@@ -43,6 +43,7 @@
   </PropertyGroup>
   <ItemGroup>
     <Reference Include="System" />
+    <Reference Include="System.Drawing" />
     <Reference Include="System.Windows.Forms" />
   </ItemGroup>
   <ItemGroup>