Try mounting a fixed partition, any not mounted partition will do. Gigolo only pops an error message that user authorization is required. From the gtk file-open dialog (2.14 and later), e.G. from mousepad's file open, clicking on the not mounted volume will correctly ask for user credentials. In function gigolo_backend_gvfs_mount_volume() at backendgvfs.c, during calling g_volume_mount(), the third parameter should be popluated as such: g_volume_mount(G_VOLUME(vol), G_MOUNT_MOUNT_NONE, gtk_mount_operation_new(window), NULL, volume_mount_finished_cb, backend); required window parameter should contain the main gigolo GtkWindow be passed there as suitable, e.g. from action_mount_cb() at window.c as GTK_WINDOW(window). Observed in xubuntu karmic, code seems same in latest git.
Created attachment 2712 Proposed patch, works on xubuntu 9.10
Thanks for patch, applied with only small changes (your GtkMountOperation object was leaked and I prefer to use GigoloMountOperation which also works for older GTK versions). Though I could not test it since I'm not sure how. But I guess you can :). Thanks.