For drawing a filled rectangle.
fillRect( x, y, width, height, isCentred=false )
Draws a filled rectangle. The x/y location refers to either the top-left corner, or the middle, depending on if 'isCentred' is false or true. The 'width' and 'height' are the total size of the rectangle.
// draws a 100x200 rectangle, that extends out to the right and down, from 10x10
fillRect( 10, 10, 100, 200, false )
fillRect( x, y, width, height, xAlign, yAlign )
Draws a filled rectangle, but also provides x and y alignment options. See the article on How Alignment Works for more information.