Compare behaviour of Pivot Components that 'pop up' a sub-window and standardise where appropriate

CalendarButton
ColorChooserButton
ListButton
MenuButton
SuggestionPopup

Things to consider

• ALT+DOWN keystroke to open
  (currently only supported by ListButton)
• Should ESCAPE cancel the selection
• Should ENTER accept the selection
• Use of TAB and SHIFT+TAB to refocus away from the Component when the pop up is showing
• arrow keys to select the first or last item when the popup visible but no selection
• Passing of focus to the popup when shown
  (MenuButton can be opened with a mouse click, but the popup isn't focused, meaning that arrow key presses might scroll the parent scrollpane)