The way I suggested would enable it to do nothing if it is not implemented (the application could check if the FILE_MANAGEMENT atom is defined, and if not, don'

The way I suggested would enable it to do nothing if it is not implemented (the application could check if the FILE_MANAGEMENT atom is defined, and if not, don't bother defining it since it is worthless; if it is defined and it takes that selection, but the file manager isn't running, nothing will happen, so that is OK too), so I don't know what is the problem with it. But if the program supports highlighting text with the mouse and putting that in the PRIMARY selection, that could work too (and you can ignore the FILE_MANAGEMENT selection); the user might then define some global keyboard command or icon in the window manager or desktop environment, which causes it to display a menu of options for dealing with the file named in the PRIMARY selection. But in the case of filenames, the problem is determining what directory it is relative to. In the case of other stuff such as measurement numbers that you want to convert, using the PRIMARY selection in this way seem it would work; the application program need not be aware of such thing in order to enable it to work, since it is a separate program that would deal with the measurement conversion. Either way, for people who do not want it, nothing happens! (I probably don't need it myself, but maybe some users use it, I don't know)