"View tree" not working

[schuco]

Clicking "view tree"

results in URL like
https://home/hourglass-3-1/I1741
where no document ist found.

1. May there be the module hourglass-3-1 missing in my installation?
2. Instead of a standard tree view I would like the click result in display of the tree from the user defined module GVExport.
   see https://github.com/Neriderc/GVExport
   This would need an URL like
   https://home/index.php?route=%2Fmodule%2F_GVExport_%2FChart%2Ftree1&xref=I1737
   I know this would require a configuration menu for the admin settings or hacking the code.
   So could there be displayed the "Diagrams" menu by clicking "view tree"?

I like the design of this theme as it does not waste space like other themes. I would make it my standard theme if it was easyer to choose the GVExport-diagram