Lyx documents show up as unknown in nautilus. This would need a new icon, i suggest sticking /usr/share/lyx/images/lyx.xpm on top of some base mimetype icon (which i can't find anywhere). And it would need to add a default entry to the "open with" list. Reproducible: Always Steps to Reproduce:
Created attachment 66031 [details] Proposed icon Here is a placeholder icon, until someone can do a proper one.
The following line needs to be added to /usr/share/applications/lyx.desktop: MimeType=application/x-lyx then upon running update-desktop-database, lyx should be the default application for lyx files. By putting the attached image in /usr/share/icons/gnome/48x48/mimetypes, it will be automatically used as the default icon.
Created attachment 66033 [details] Proposal v2 Made the text clearer
I have added your icon and the desktop file change to lyx-1.4.0-r1. Please try it out and reopen the bug if it does not work! Thanks for providing the icon and the way to install it.