Which are the files responsible for the menu on Gimp 2.6?

[rich2005]

If not able to fix your installation then there are Gimp 2.6 packages for ubuntu distributions here:
https://launchpad.net/~malcscott/+archiv.../+packages

I did try using the PPA for a regular install in a Ubuntu 16.04 (virtual machine) but ran into update / dependency issues. However downloading the relevant packages and installing manually (sudo dpkg -i *.deb) worked. With a caveat, some warning messages: screenshot: https://i.imgur.com/ZcKwKAS.jpg

Warning messages apart, it seems to work although no real testing for whoopsies. screenshot: https://i.imgur.com/NeTwfv0.jpg