I have CorelDraw 11 and I am useing the PhotoPaint in it.
If I open am Image that has a somewhat Black Background I do this.
I use the Lasso Tool and Cut what I want and past it into CorelDraw work Space.
And then I can always Dabble click the image in the CorelDraw workspace and it re opens it in PhotoPaint and I can use the wand Tool to remove anything from the Image I do not want.
And I do have the Tab Display Mask Merquery selected.
But I can always see an Outline of the Parts I remove.
So I would gess I have to set my Father to Zero for my Laso Tool.
But I do not see any Father setting????
I would suggest importing your picture directly into Corel Draw and then trace your crop line with the bezier tool and power-clipping the image inside that shape. You can then covert a copy to a bitmap and further edit that or go back and edit the original powerclipped version without losing anything.