Drag-and-dropofdropScripts from the MAX toolbars is possible. DropScripts are simply macroScripts with 'on drop' and optionally 'on droppable' handlers, as defined above. If a macroScript button on a toolbar has an 'on drop' handler defined, you can drag that button off the toolbar to initiate dropScript drag-and-drop.
Note the use of the 'showInViewport' property at material level.