Copy / Cut / Paste / Import / Export

Copy / Cut image or selected content:
to copy press Ctrl+C key combination on keyboard
to cut press Ctrl+X key combination on keyboard

note: ability to copy / cut content outside the program depends on browser engine

note: copying image with transparency outside the program, also depends on your current OS clipboard functionality

Paste - to paste image content onto a layer or a mask press Ctrl+V

Import Image - you can import an image that is saved on your computer.
File->Import Image and choose the image file.
This will import the image onto an active layer in your project

supported image formats for importing:
png, jpg/jpeg, gif, bmp, webp, webm, svg

Export Content
File->Export Content - this will export selected content of a layer or a mask as png. Will export whole layer or mask if no selection is active.