So far, so good - FDM 6.2 Alpha latest, Firefox Nightly 69.0a1 (2019-06-23) (64-bit), and running in Sabayon Linux (Gentoo derivative).
I had to manually extract the files from the .deb cpio but other than that no issues thus far - FDM loads automatically at startup and everything I have thrown at Nightly to DL (thus far) has been captured by FDM.
Great to see the familiar DLM on my Sabayon laptop, now, too.
One note: When run for the first time, the default size dialog box shows info pane at the bottom, but it is truncated, and if one tries to adjust the height without making the whole window larger, it does nothing - you see the cursor change to the cursor the system has set for altering the user that the area is resizable
(typically conjoined up/down arrows for vertical resizability and conjoined left/right arrows for horizontal resizability) but
nothing actually happens when you try to drag the info window up to show the partially hidden information.
It would be good if the arrows did not indicate resizability when it cannot actually be resized.
It would be even better if a small popup would explain to the user that in order to see the information / resize the info pane, you need to make the whole window larger.
Of course, I can also see validity in simply having the info show completely in the main window to begin with, but I can also understand if the devs think that would be a waste of too much real estate.
And, to be fair, it's extremely minor - a simple thread here in the forums may be more than enough.