Range: valid graphic URL
Specifies the graphic that's used to draw the background of the control, up to the
current position of the icon graphic. A dynamic mask is applied to the reveal
graphic in order to hide the portion that's to the right of the icon.
As the user adjusts the control by moving the icon, the mask adjusts as well.
Graphic files can be in any format that Flash can import dynamically (JPEG, PNG, GIF, SWF). If SWFs are used, graphics can
be located in a frame on the main timeline or as exported symbols (class objects) in the library. URLs to SWFs must be appended
with either '#' or '@' followed by either a frame label or class name. If timeline frames are used, it's best to include a blank frame at the start of the movie, with a stop() command.
align: the string 'top', 'left' or 'center'
angle: floating point number (degrees)
bind: an object ID, period and property name
back: valid graphic URL
border: positive integer (pixels)
bordercolor: six character hex color value
color: six character hex color value
disicon: valid URL to a graphic
grad: floating point number less than 128
height: integer (pixels) or '*', '**'... (proportional)
icon: valid URL to a graphic
max: floating point value
min: floating point value
overicon: valid URL to a graphic
reveal: valid graphic URL
symbol: a valid SWF URL, followed by an ampersand and class name
width: integer (pixels) or '*', '**'... (proportional)