+4  A: 

Don't do this; it's not what users expect. A dock icon and menu bar go together. If you want to get both a dock icon and menu bar icon in your UIElement app, use TransformProcessType.

If you really must, you can draw your own menu bar window (if you use the appropriate window level it'll appear over the top of the existing menu bar).

Nicholas Riley
How would I draw my own menu bar window?
Joshua
Create an unadorned window starting to the right of the Apple menu and start drawing in it. If you want the menu bar to look like the OS X menu bar, see the Appearance Manager documentation and HITheme.h. You can get the menubar height and other such measurements with GetThemeMetric, then use functions like HIThemeDrawMenuBarBackground and HIThemeDrawMenuTitle to draw backgrounds; HIThemeGetUIFontType, HIThemeDrawTextBox and the like to draw text. You can probably get away with using standard menus assuming you can either fix or disregard the rounded top corners on 10.5.
Nicholas Riley