Share dropbox PID

buildFHSEnv {

  name = "dropbox";

  # dropbox-cli (i.e. nautilus-dropbox) needs the PID to confirm dropbox is running.

  # Dropbox's internal limit-to-one-instance check also relies on the PID.

  unsharePid = false;

  targetPkgs = pkgs: with pkgs; with xorg; [

    libICE libSM libX11 libXcomposite libXdamage libXext libXfixes libXrender

    libXxf86vm libxcb xkeyboardconfig