Well, to iso partition i cannot add files and use it like usb drive. But i learned how to make syslinux partition from syslinux.org. It's two simple command to create a syslinux partition of for example 2GB. i copied the files from non-bootable binary image. It's also possible to chroot to the chroot directory and add some packages, create a new squashfs file and replace the one in usb stick.
Btw, mount error disappeared after i added task-gnome-desktop package and the binary.img got created in root directory where i run lb build. When there was mount error , it was being created inside chroot directory. But I'm not sure if that was a luck ! It sometimes work, sometimes not. Hybrid ISO always works, so if i decide to create a different ISO i will get the files from it in binary directory and just add to the usb stick. Great product , keep up with the development ! Thanks Mina
