Provide access to the values of XDG_DATA_DIRS and XDG_DATA_HOME

The documentation of CreateDesktopEntry says: "desktop entry is stored [...] in the location specified in $XDG_DATA_DIRS/applications or $XDG_DATA_HOME/applications, including the default paths for both, as defined by freedesktop.org."  However, there is no way to find out what values of these variables end up being used within the installer framework. 

That is, once CreateDesktopEntry has been called, the installer framework has determined these values, but there isn't anyway to then access them for use in installer scripts.

It would be great if the resulting directory used by QIF for CreateDesktopEntry was made available via a function call or installer.value, so as a user I don't have to duplicate the effort to try and "reverse engineer" what QIF ended up using. 

My use-cases for this are:

a.) First, I have a user-option at the end of the install to create a desktop shortcut.  I execute xdg-desktop-icon to copy the "run program" shortcut previously created using CreateDesktopEntry, but of course to make use of that, I need to know where it is.

b.) Second, I create a root menu for my application (rather than having it show up under one of the pre-defined ones like "Other").  I execute xdg-desktop-menu to define the root menu and install all the previously-created entries (via CreateDesktopEntry) under this root menu.  Again, to do this, I need to know where the previously-created entries are.