Although I did explain this in post #8 & #10 https://www.gimp-forum.net/Thread-Newby-...0#pid31130
I'll give you a step by step with a method you seems to prefer... selections.
Create your safezone with a selection in normal mode (not addition), you can create guides from selection if you wish as a visual reference for later
then go to Select > Save to Channel, the channel tab got in focus and the newly created channel should be selected by default as well, it's called Selection Mask Copy,
then go to Select > None.
then go to Colors > Invert (like that it's ready ready to cut out)
then go back to the layer stack/dialog (layers are all un-selected), thus select/click the layer you want to copy from
make a new selection in normal mode > yes the first selection will disappear, that's ok you saved it to channel
then copy/paste your thing > a floating selection appears in the layer stack, commit it on a new layer (Layer > To New Layer)
Use the move tool to move than new layer to its new place
use the a transform tool you need to what you need to do
once it's done go to the Channel tab/dialog, right click on Selection Mask Copy a context menu opens, select Channel to Selection
Go back to the layer stack/dialog, click on the layer you have made some transformation, and hit that Delete button
done
I'll give you a step by step with a method you seems to prefer... selections.
Create your safezone with a selection in normal mode (not addition), you can create guides from selection if you wish as a visual reference for later
then go to Select > Save to Channel, the channel tab got in focus and the newly created channel should be selected by default as well, it's called Selection Mask Copy,
then go to Select > None.
then go to Colors > Invert (like that it's ready ready to cut out)
then go back to the layer stack/dialog (layers are all un-selected), thus select/click the layer you want to copy from
make a new selection in normal mode > yes the first selection will disappear, that's ok you saved it to channel
then copy/paste your thing > a floating selection appears in the layer stack, commit it on a new layer (Layer > To New Layer)
Use the move tool to move than new layer to its new place
use the a transform tool you need to what you need to do
once it's done go to the Channel tab/dialog, right click on Selection Mask Copy a context menu opens, select Channel to Selection
Go back to the layer stack/dialog, click on the layer you have made some transformation, and hit that Delete button
done