Organizing Actions
Keyboard Shortcuts
While it's not directly possible to assign arbitrary keys to action groups, you can use the keyboard shortcut to trigger the action group menu Alt+A in combination with another character from the action group name. Simply decide on the character and prefix it with &. You can then use Alt+A and the character to trigger the action group.
An example action group &Uppercase can be triggered by Alt+A plus U.
Submenus in the Action Group menu
If you use the # in your action group name, Mp3tag uses anything before the # as name for a submenu and anything after as a menu item in that menu. By that, you can organize action groups that belong together.
An example action group Default values#Set COMMENT would create a submenu Default values and would list the action group Set COMMENT within this menu.
Pro tip: you can combine both tips, e.g.,
&Default values#Set &COMMENTto trigger the action group by pressing Alt+A plus D plus C.