How can I get the width or height of the dock in Mac OS X so I can resize a window properly?
The following example AppleScript code will return the size of the Dock:
tell application &quot;System Events&quot; to ¬
    tell application process &quot;Dock&quot; to ¬
        set dockSize to ¬
            the size of list 1

return dockSize

If you want the width and height:
tell application &quot;System Events&quot; to ¬
    tell application process &quot;Dock&quot; to ¬
        set {dockWidth, dockHeight} to ¬
            the size of list 1


return {dockWidth, dockHeight}