thanks for asking.

You can deactivate the Default Behaviour, if you want. All you have 
to do is untick the checkbox in front of it in the "Mapping" table.

The purpose of the Default Behaviour is to give you the ability to 
specifiy a fallback when no supported application is running or in 
the foreground.

Many people have asked about the possibility to make RB show the root 
menu when pressing the menu button. I'm still not friends with that 
idea as it breaks a lot of things in the RB concept (i.e. you 
certainly don't want RB to go back to the root level when you were 
previously amidst browsing your music), but I'm working on a solution.

For now, keeping the "left" button pressed while the menu is visible 
will always bring you to the root level of the menu quickly.

If you just want to see the root menu level in those cases where you 
are currently seeing the Default Behaviour's context menu, turning it 
off as described above will already give you the desired functionality.

Hope that helps.

Best regards, 
Felix Schwarz