I've been self-compiling mame on Ubuntu 17.10 and one of the things I've noticed is that mame doesn't have a dock icon.
If you don't have a dock icon, the mame windows get grouped way down at the bottom of the dock and you have to scroll all the way to the bottom to get them.
I usually launch mame from a terminal so I want my icon to sit right under the terminal icon near the top.
No icon means that I can't even drag it up to the terminal by hand because it sticks to the bottom.
I'm running wayland and I guess that means it's Ubuntu Gnome Shell, then?
So let's create a "mame64.desktop" file and put it in ~/.local/share/applications/mame64.desktop
and inside the file we'll put this:
Exec=/pathto/mame191/mame/mame64 -rompath '/pathto/myroms' -plugin console -debug
You have to set the pathto part for where you've put mame. You don't need the -rompath or -plugin console or -debug if you don't really want to use them. I've just copied my normal command line into the Exec line.
And make yourself an icon, launch gimp and make a 64x64 icon. I just made the word "mame" and stuck it in the graphic. Franklin's no frills, eh? You can search google for "mame icons" and there's some nice ones.
Save it in your home directory, then copy it to /usr/share/pixmaps/
sudo cp ~/mame64.png /usr/share/pixmaps/
Now you should be able to launch mame and be able to move it up in the dock and get it to remain on the dock by right clicking and "Adding it to Favorites".
I got tips on how to do this from this page:https://askubuntu.com/questions/967409/cant-add-custom-desktop-files-to-dock-17-10