How to copy a temporary edit image with changes to another application?

[testcb00]

(01-13-2022, 07:44 PM)rich2005 Wrote: That checker pattern is transparency, the alpha chanel

Before anything else, turn that off. Layer -> Transparency -> Remove Alpha Channel

Now you can make the selection and Edit -> Cut  
next Select -> None and Edit -> Copy before pasting...where you want to paste.

If you can get see this, 30 second animation: https://i.imgur.com/azBtnCx.mp4

Thank you very much, that's what I want.
It seems that there are no option to set "Remove Alpha Channel" by default.
Anyway, I can simple right click toolbox and do the job. Now I can move to GIMP.