by drake » 23 Apr 2012, 10:35
Because this is the meaning of any menu - on the web or just on your computer - your action of choosing a menu item is followed by the effect of that item. In Windows or Mac or whatever system you have on your computer the effect is to opening a window or a submenu, on the web the effect is to opening a page where you put something to show to the people or a submenu...
If you don't wish to open anything (in the case that the effect needed is just to open another menus - a drop-down submenu) you can use a "link" with the url adrress "#" (or you can set the top level page from menu to not go anywhere at Additional Options for Suffusion, below the edit screen (thick: "Do not link to this page in the navigation bars"). The child pages of this page will be the items of submenu.