Provide selection capabilities for DOM elements, geared to <select multiple>.
click: select elementctrl + click: add element to current selectionclick + move: select elements while draggingctrl + a: select all elements within focused listctrl + shift + a: deselect all elements within focused listctrl + click + move: toggle selection while draggingshift + click: select range from nearest last selected element to clicked elementshift + ctrl + click: add range to current selection