Changing shortcut keys
In help of user panel is write "Shortcut keys can be used to navigate in the Zimbra Web Client (ZWC ) and you can create your own shortcut key combinations. " I ask WHERE CAN IN CHANGE COMBINATION OF KEY SHORTCUT because I can't find in preferences that ability. Only list that shotcut keys.
Look for the AjxKeys.properties and ZmKeys.properties files in your installations, there are some that change the key shortcuts for different languages in L10N. I think they're somewhere under /opt/zimbra/jettty/webapps/zimbra/WEB-INF/classes/
Maybe you can change this to whatever you need to do. I don't know if you can add a new action for key combos, but it's the first place I'd look.