I must be missing something because it seems that I can't get the ESI tool to allow me to edit a message or header that has been defined. Sometimes I make mistakes and want to assign different variables to a message, but can't seem to get the tool to allow me to go back and edit.
Once the message is already added in device XML, go to tree view (on right side of tool), right click on message and you will see menu options. CLick on 'EDIT' and it will take you back to wizard mode in Edit mode.
If you are already in the wizard (starting from "select event from log file"), menu options are grayed out so that user does not try to tamper the header or message from those menu items (lets say you are going thru wizard for a message and delete the message from tree view). Once you exit the wizard using "Cancel", you can use tree view for those menu options like Edit.