Inside my control, I have:
ContextMenu = new ContextMenu();
ContextMenu.MenuItems.Add(new MenuItem(\"&Add Item\", onAddSpeaker));
ContextMenu.MenuItems.A
If you are using the Designer, place a single hyphen "-" as text the same way you would name your menu items. After hitting enter, the separator will be created.
This works just as well as the dash, and i suspect the Winforms will translate the dash to a ToolStripSeparator. I for one think this solution is more obvious for anyone who has to maintain the code.
yourContextMenu.Items.Add(new ToolStripSeparator());
In WPF:
ContextMenu.MenuItems.Add(new Separator());
Perhaps in later versions of Visual Studio they made this simpler. I'm using VS 2012. You can add a separator via the forms designer. 1) Select/Create a MenuStrip. 2) On "Type Here", right mouse. 3) Select "Insert". 4) Select "Separator". 5) Drag the new separator to the text you want it to be above. Done.
Set the text property to a hyphen.
I believe it's just a dash:
ContextMenu.MenuItems.Add("-");