Comment 4 for bug 455378

You should be able to resize windows beyond work area edges with Alt + Middle click (by default), which can be configured in Resize plugin options in ccsm. Does that work there?

Resizing by dragging window borders is limited to work area by Compiz to prevent window edges from becoming inaccessible while resizing by going behind panels or beyond screen edges. To handle this issue, Metacity instead uses snapping during resize, which Compiz 0.8.4 lacks.