If I interpret what you want correctly, you can do it a couple of ways, depending upon whether you want total control of what the menu looks like or you want a system looking menu.
If you want the system looking menu, use an event structure and code in mouse and menu events to generate it. It has been awhile since I did this, so the details are hazy, but it is written up in the LabVIEW help. Essentially, on a menu activate event (when someone does a right click on a control), set up the menu the way you want it. They will then select the menu and you have to handle the menu select. If you want a menu on left click, you need to intercept the mouse down event (use mouse down? event) on that control and convert the mouse button from 1 to 2, then follow the above instructions.
If you want to show something other than a menu (e.g. a tab control), you will need to create a separate VI containing the menu items. You can make the background of the VI transparent, so it will appear to be floating over your other panels. On a mouse down/up/enter/??? on your control of interest, launch the separate VI. You will probably want to make the separate VI modal (see VI properties - appearance) to avoid issues with it disappearing behind your other code. For information on how to launch separate VIs and how to get data into and out of them, see this series of posts.
If neither one of these helps or you need more info, keep posting. We will try.
