> Under TP9, I can't find a way to do this - when I double-click on the ".TPDB8" file it seems that it always tries to open whatever folder was open the last time TP ran or, if I set the Preferences -> Startup -> Initial Folder -> Specific Folder option, that folder is always used no matter what database I open (i.e., that preference is stored as a per-user setting rather than a per-database setting).
Yep, that's correct. TP9 doesn't have a database-specific default folder to start in anymore (because it no longer stores parts of its settings in a database-specific .tdo file - there's only thumbs9.ini now).
> Is there a way to have TP open so that it defaults to the same folder that the database is in, or so that it defaults to the Windows default folder for the process, or to configure the startup folder on a per-database basis?
Alas: No, no and no.
You can specify a database on the command line though, and so, you could create separate shortcuts (desktop icons) that each launch TP with a different database.
However, to change the default startup folder, you'd have to edit the thumbs9.ini file before TP9 is launched. Perhaps you could write batchfiles that use a utility like [link=http://www.horstmuc.de/wbat32.htm#inifile]IniFile[/link] to do that automatically for you. The entry to change is StartupFolder= in the [Startup] section.
Combine the above suggestions and you could have a few different shortcuts (to the batchfiles) on your desktop that each launch a different database and that make TP9 start in the desired folder.
If that's too complicated, another way to quickly navigate to certain folders is to make them 'favorites' in ThumbsPlus. Use Ctrl-R to add a folder to your favorites, Ctrl-Shft-R to edit the favorites, and Tree | Go To to navigate to a favorite folder (or click the big yellow Star icon above the tree panel).
I hope this helps.