Is there a way to add/change a toolbar (at the top)?

[multicart]

Or can we users "only" customize a lot of other things (e.g the menu and the button bar (at the bottom))?

regards, m.

[Jungle]

You can enable "entire-row" Quick launch bar in the Core Settings > Layout. Then you can e.g. drag'n'drop exe-files on it and insert user defined commands.

[multicart]

ok, that is nice, thank you