Getting the ALT key working

If your using KDE you may want to modify the ALT key behaviour Open Control Center --> Desktop --> Window Behaviour --> Actions

And change the modifier to key to something else.

Otherwise you can use right alt key (Alt Gr) only.

Java Virtual Machine

When you using Ubuntu with Gnome. You could install josm with the repositories. If you don't install java do this. Then you could start josm in the bash with the command josm. Sometimes there is a Error like this:

No valid JVM found to run JOSM.
Please install one of those mentioned in README.Debian
or set the JAVACMD environment variable prior running josm.

Then you have to make a symbolic link in the folder /usr/bin/ like this:

  sudo ln -s /usr/bin/java /usr/bin/jamvm

Then you could start josm.