[jQuery] blockUI cursor bug when overlayCSS backgroundColor is empty/transparent

[Tawl]

I know there's already a couple of posts about IE cursor issues, but
this one is slightly different I think.

If you set the overlayCSS backgroundColor property to an empty string
or 'transparent', IE will not change the cursor when blocking the UI.
E.g.

            $.blockUI({
                message: null,
                overlayCSS: { backgroundColor: '' },
                fadeIn: 0,
                fadeOut: 0
            });

The above will not change the cursor in IE.  I have worked round this
by setting the overlay properties to white with zero opacity instead,
which does produce the correct cursor behaviour:

            $.blockUI({
                message: null,
                overlayCSS: { backgroundColor: '#fff', opacity: 0 },
                fadeIn: 0,
                fadeOut: 0
            });


I guess this is more of a tip for anyone else who encounters the same
issue.