I have just posted a note on their reatures request board - see if anything comes of it.
Stupid me - if you exit from the system tray it leaves a couple of things dormant in the task manager (for when you restart X1) but it does close files so you can work on them.
One warning about indexing multiple Outlook archives ...
When you specify extra PST files for indexing extra Outlook 'Profiles' are produced. Nothing bad in that and you don't have to think about them ... unlesss ...
If you want to uninstall X1 you need to delete the profile from Outlook manually as X1 doesn't tidy up. Further more when you uninstall X1 it doesn't remove the index from your system so that if you then later reinstall it will pick up from the old index where it left off. By that stage the Outlook profiles originally set up and used by X1 probably don't exist. You get a harmless looking complaint from X1 to which you glibly click OK (as we all do) and then the email is read - all is well with the world. Until that is you reopen Outlook when you will find the archived PST files you have accessed are loaded at Outlook startup so that you have a long wait (if you have a large archive of emails) - also because they aren't associated with the current profile you can't close them to remove them! The only solution I have found is to close Outlook, rename the main live Outlook PST file, delete the profile (from Control Panel > Email applet) and then restart Outlook and allow it to build a new profile. You then have to enter all your email account settings again as they are part of the profile and import you old email (either by swapping live PST file, or Open and copy you old PST file). PITA - and right royal one too.
The best solution is to kill off the index in X1's options before you uninstall and then physically delete the index folder (usually in %USERPROFILES%\Application Data\) after the uninstall is complete, then manually delete the extra unneeded Outlook profiles.