text: The combo box supports the expanded attribute selector with possible values of true and false . true is used when combo box displays one of pre-defined embed sizes, thus should take all available width. false is used when custom size option is selected in the combo box, so it should shrink to allow space for custom width and height input fields.
  The combo box has a "drop down" button on the right and it is controlled with the following CSS class selector:
  When "Custom Size" option is selected in the embed size combo box the dialog box displays two extra input fields to the right to allow the user to enter a custom embed size. Those fields are wrapped in a container that is controlled with the following CSS class selector:
  Thumb supports the state attribute selector, which can be used to apply different skins to different thumb states: up , down , over , and disabled .
  It is not possible to position scroll buttons using CSS top , left , bottom , and right properties. Instead, the viewer logic automatically positions them.
  These buttons support the state attribute selector, which can be used to apply different skins to different button states: up , down , over , and disabled .