diff --git a/Source/ExcelDna.IntelliSense/ToolTipForm.cs b/Source/ExcelDna.IntelliSense/ToolTipForm.cs
index 23bb4ca..4bd7bdb 100644
--- a/Source/ExcelDna.IntelliSense/ToolTipForm.cs
+++ b/Source/ExcelDna.IntelliSense/ToolTipForm.cs
@@ -72,7 +72,8 @@ protected override void WndProc(ref Message m)
             const int WM_MOUSEACTIVATE = 0x21;
             const int WM_MOUSEMOVE = 0x0200;
             const int WM_LBUTTONDOWN = 0x0201;
-            const int WM_LBUTTONUP = 0x0202;
+            const int WM_LBUTTONUP = 0x0202;
+            const int WM_LBUTTONDBLCLK = 0x203;
             const int WM_SETCURSOR = 0x20;
             const int MA_NOACTIVATE = 0x0003;
 
@@ -92,7 +93,8 @@ protected override void WndProc(ref Message m)
                 case WM_LBUTTONUP:
                     MouseButtonUp(GetMouseLocation(m.LParam));
                     return;
-                case WM_SETCURSOR:
+                case WM_SETCURSOR:
+                case WM_LBUTTONDBLCLK:
                     // We need to handle this message to prevent flicker (possibly because we're not 'active').
                     m.Result = new IntPtr(1); //Signify that we dealt with the message.
                     return;