on second thought, don't toggle the global config option on show/hide menu. Also make it a function in mainform

BizHawk.MultiClient/MainForm.MenuItems.cs

@@ -1410,8 +1410,7 @@ namespace BizHawk.MultiClient
 
 		private void showMenuToolStripMenuItem_Click(object sender, EventArgs e)
 		{
-			Global.Config.ShowMenuInFullscreen ^= true;
-			MainMenuStrip.Visible ^= true;
+			ShowHideMenu();
 		}
 	}
 }

BizHawk.MultiClient/MainForm.cs

@@ -2425,5 +2425,10 @@ namespace BizHawk.MultiClient
 
 			StateSlots.ToggleRedo(Global.Config.SaveSlot);
 		}
+
+		private void ShowHideMenu()
+		{
+			MainMenuStrip.Visible ^= true;
+		}
 	}
 }