The universal appeal for portable applications lie in the fact that they aren’t associated in any way with the host computer. You can run them from a hard drive or a flash drive. You can move portable applications from one drive to another, or between computers and it takes all associated data and settings along with the program. If you don’t like a portable application, you can simply delete it because there are no file or registry leftovers to deal with. Portable applications operate almost in stealth.
One drawback of portable applications is that it is not possible to make them the default file handler for specific types of files, at least, not through the “Default Programs” applet in control panel, because as far as the operating system is concerned, the portable application doesn’t exist. To overcome this problem, we have to use third-party extension managers.
eXpresso is a small program that makes temporary association of filetypes with portable applications. All associations are recorded as relative paths in an ini file, without writing anything to the Registry of the host computer. The filetype association is active as long as eXpresso is running. The portable applications disassociates itself from their respective filetypes as soon as the user closes eXpresso.
eXpresso itself is a portable application.
To make an association, all you have to do make sure eXpresso is running, and then double click on a file. If eXpresso does not yet have an association for that filetype, it will then display a window asking which app you wish to associate it with.
You can associate up to 2 different applications to a single filetype. If you hold down the Shift key when double-clicking on a file, it launches the file in the system default program. The Alt key, on the other hand, launches it in the second alternative program if one is configured in eXpresso.
You can also associate a portable application with a filetype by right-clicking the eXpresso system tray icon and then clicking on the appropriate item from the menu.
eXpresso also provides an option where you can change the path of a portable application from an absolute path to a relative path.
To stop making new file association, or override the current portable association, simply put eXpresso on Pause, or just exit it.