add focus/blur events to Button
add css className to Cell
add header to dialog and use flex layout
cancel drop events on the body
add 'click' event in places of 'Select' (deprecated)
add opts.selection for List (deprecating opts.selectable)
add focus/blur and enabled states for TextInput, save and restore cursor selection as needed
add clear (alias for deselectAll) to a Selection
add css classname functions to base class (add/remove/has/toggle)
whitespace