The Dashboard menu tab appears only if the $hide_inaccessible_menu_items = 0; since it is disabled in the install (how to enable it in the install?) and even then it appears blank.
The patch needed is to enable all widgets to be available as menu items in the Dashboard menu tab and make it enabled and have the Dashboard functionality removed from other tabs. Possibly the widget display sql can have the WHERE clause tweaked to not care about the menu tab it is to be displayed in and make a decision to display it only if the Dashboard menu tab is selected.