> You said that you created the mask in a clever way.. How exactly did you
> do this?

I know about 1% of what is possible with mask creation and manipulation, so
this may look primitive to more skilled users, but here's a summary (I may
have actually learned this technique from a Corel newsgroup).

On a copy of the image, I used contrast enhancement (called level
equalization in version 8) from the "Adjust" menu to push the black dress
into an extreme range by sliding the input value clipping markers as shown
in the attached image.

After that I converted the image to black and white, adjusting the settings
as shown in the other attached image to complete the isolation of the area.
There were some areas that I did not want to be masked that I then painted
out. The image is actually an inverse of the area that the mask is needed
for (white is in, black is out), so either invert the black and white colors
before saving as a mask file (Image/Transform/Invert), or invert the mask
after loading it into the original image. I feathered the mask (Mask/Mask
Outline/Feather) by a factor of three and a direction of "middle".