Comment 5 for bug 739405

A solution in gtk2-engines isn't going to fix this bug in Firefox (it needs to be removed entirely in Firefox, and you can't do that from the theme engine). It also won't fix other applications where the grippy obscures another UI element.

However, if you just have a problem with the colour of the resize grippy rather than the fact that it obscures other UI elements, feel free to report a separate bug against the theme or theme engine.