Am I the only one who routinely has to re-type the whole bug report? I usually type first, then try to attach a file via drag and drop on the “Attach a file” button.
Result: Firefox helpfully opens the file in the tab I was creating the bug with and all previously entered data is lost 
(No, immediately going back does not restore it.)
Can this be fixed? Any tips, tricks or workarounds? Where would we report such “Meta-Bugs”?
Jokes aside, although sending an infrastructure-specific bug report is possible in theory, it might be difficult to fix in the near future in practice, so you can try to decrease the probability of the issue happening, e.g. by attaching files after sending the initial report.
Been there, tried that. But then I forget and it happens again.
Bugzilla is pretty ancient, and there isn’t a lot of energy for real redesign of basic workflow or new features. I don’t think it accepts drag and drop uploads at all. I really do think getting in the habit of submitting your initial info first and then attaching in the next comment is the best suggestion we are going to get.
Yes, that’s quite obvious when you look at it 
Tbh I think I just needed this to share my frustration about this issue, it is biting me every now and then and it hurts every time. I’ll try to get into that habit, but I think we all agree, that in an ideal world the tools would be designed in a way that prevents mistakes and negative experiences like that.
On the technical aspect: When you remember to click the “Add an attachment” button first, you can drag and drop files on the “Browse…” button, I think that’s a Browser built in, not a Bugzilla feature. However, in cases of bad aim i.e. slightly missing the “Browse…” button or if you are feeling lucky and try dropping on the “Add an attachment” button, you get what you deserve: Instant punishment.
We feel your pain.
This is actually a common problem for some web services.
A clipboard manager and/or a text editor can help to mitigate it to a certain extent.
I personally use GPaste/Gedit and if I’m unsure about the result, then Ctrl+A & Ctrl+C.
Understanding Bugzilla is like understanding Tax returns. You’re a genius already for being able to successfully report a bug.
I gave up on using that tool and probably many other people that could be contributing also did