How do you copy and paste things on tux paint?
The images you've saved in tux paint are files. On my computer I
can locate them by navigating to my home directory and opening the
hidden directory labeled '.tuxpaint' then opening the directory
labeled 'saved'.
"The directory/folder where Tux Paint saves files may be
changed. This can be used to save pictures in a student's home
directory on a network drive or shared drive, rather than locally
on one particular workstation."
- http://www.tuxpaint.org/features/