fix #13400 Cannot enter characters when adding ToolStripMenuItem1 and then adding ToolStripMenuItem2 after pressing enter in DemoConsole application

Author: Epica3055

src/System.Windows.Forms/System/Windows/Forms/Controls/ToolStrips/ToolStrip.cs

@@ -4579,7 +4579,11 @@ protected override void WndProc(ref Message m)
             SnapFocus((HWND)(nint)m.WParamInternal);
 
             // For fix https://github.com/dotnet/winforms/issues/12916
-            ToolStripManager.ModalMenuFilter.SetActiveToolStrip(this);
+            // Narrow down the range, because ToolStripDropDown is ToolStrip too. we only need to set outer ToolStrip active.
+            if (IsOuterToolStrip(this))
+            {
+                ToolStripManager.ModalMenuFilter.SetActiveToolStrip(this);
+            }
         }
 
         if (!AllowClickThrough && m.MsgInternal == PInvokeCore.WM_MOUSEACTIVATE)
@@ -4646,6 +4650,21 @@ protected override void WndProc(ref Message m)
             // WM_DESTROY.
             _dropDownOwnerWindow?.DestroyHandle();
         }
+
+        static bool IsOuterToolStrip(ToolStrip toolStrip)
+        {
+            static ToolStrip getParentToolStrip(ToolStrip toolStrip)
+            {
+                if (toolStrip.Parent is ToolStrip parent)
+                {
+                    return getParentToolStrip(parent);
+                }
+
+                return toolStrip;
+            }
+
+            return toolStrip == getParentToolStrip(toolStrip);
+        }
     }
 
     // Overridden to return Items instead of Controls.