If I understand your question, you want to move a selection that has a layer mask to another image. If that's what you want, don't grab just the selected image, grab the layer with the mask and move that entire layer over.
I have two images open - one with a family, one with a family member taken separately that they want added.
I first masked the background from the individual member:
[ATTACH=full]121404[/ATTACH]
Now, I click and activate that masked layer, then click and hold on a spot on the layer next to the mask - not on the mask or on the image:
[ATTACH=full]121405[/ATTACH]
Now while still holding down on that layer, drag it over to the tab where your second image is, your second image will pop up, drag the layer down towards the center
and let go (if you're asked about profile mismatch, choose either to convert it and stay with it as is)
[ATTACH=full]121406[/ATTACH]
Now you can manipulate your image, edit the mask, make whatever change you have to make.
Is this what you're asking?
- Jeff
