Hi Daniel!
Yes, NextSTART can do this, but note that not all themes provide bitmap support for horizontal menus: some of the themes might look odd and you will have to try different themes until you find a suitable one.
First create your new menu using the built in Menu Editor. There is a tutorial on how to do this at
http://www.winstep.net/help/tutorial/intro.html
but keep in mind it was written for NextSTART v2.x, so the Preferences configuration is quite a bit different now, although the basics remain the same. Give the new menu a meaningful name, let's say 'Mac'.
If you find it easier, just create the new menu using the Menu Editor and leave it blank, you can fill it with items via drag & drop + right click context menu actions later.
Now go to the Hotspots Editor:
Create a new hotspot. If you want your Mac-like menu to be always on screen and work independently of all your other menus, then give it a special group name and enable the 'Auto-Run' option - the later will make the hotspot activate automatically (thus opening the associated menu) every time NextSTART runs.
Select some way you would like to activate your new menu (for instance, a mouse pointer bump in the top left screen corner) in the
Launch With section.
Disable the 'Snap to Mouse' option in the
Initial Position section so the Mac menu appears at (0,0), i.e.; top of screen.
Now, in the
Hotspot Action section, select 'Show Menu' from the pull up menu. Right next to it, the
Menu Name section will display a list of all your existing menus. Look for your 'Mac' menu in the Menu Name combo box and select it.
Change 'Close Menus Automatically' to 'Parent Menus Stay Open' in the pull up menu and enable the 'Use Reserved Screen Area' and 'Horizontal Menu' options.
Click Ok and make your new menu pop up using the hotspot activation method you chose previously in the
Launch With section.
If you decided to populate your new menu via drag & drop and the right click context menu, then you can do so now. In such a case, your new 'Mac' menu should appear saying 'Empty'. Just drag & drop a file (doesn't matter what, you can change or delete the entry later) into where it says 'Empty'.
To add new vertical sub-menus, you can now right click on the new entry and select 'Insert' from the context menu. Change the Command combo box from 'Run Program' to 'Show Menu' in the
New Item Properties dialog box that pops up and give your new sub-menu a meaningful name.
The new sub-menu entry will now be added to the 'Mac' parent menu. Click on it and an empty, vertical, sub-menu should open. Populate it via drag & drop and repeat the above operation for all the sub-menus.
When you're done, just right click on the first item you added (which is not a sub-menu) and delete it.
Not also that there are options specifically for Horizontal Menu behavior in the
Menu Preferences tab of NextSTART Preferences and that you can prevent maximized applications from overlapping your horizontal menu by changing the top edge value of the Reserved Screen Area in Global Preferences.
Hope this helps!