Hi @ all...
maybe too late

. But I figured out, that the easiest way to create an empty floppy image is:
- Creating an empty file on your host system (really empty... create a for example a .txt - file...)
- Rename the file ending from .txt to .img
- mount it in your guest system by right-clicking the floppy-disk-symbol in the bottom of your VM-window
- There should appear the Manager for virtual media. There you have to browse to your really empty former .txt - file.
- double-click it
- click ok
so you have mounted an empty, unformatted virtual floppy disk to your guest system. It doesn't matter if it is a linux, windows, DOS, vista, or whateveryouinstalled-OS
The last step is to format the disk on your guest system. But this differs from each OS and hopefully it will work
Btw: I don't think that it is a not-built-in-feature. You just creating disc-images as easy as mounting for example existing .ISO - images...
best wishes and greetings from vienna
DaLaunge