Helen: I don't know what's happening with using the set reader font options and the seeming loss of the database on the device. Because of this and other font discussions, I spent a bit of time using it yesterday without any problems. If you are willing to risk it again, could you run calibre in debug mode and post or send me the log? Maybe I'll be able to see what is happening.
For the controls on the dialog, the only thing I can say is
. I had hard-coded the number of values in the line spacing spin button and that didn't match how many the firmware now has. That meant if the line spacing was set to 2 (the ninth stop on the slider) or higher and you retrieved the configuration, what was displayed was inconsistent. I'll have a fix out for that later today.
As to the negative margins, I don't know what is happening. If I set negatives in the database or config file, they seem to be treated as zero margins. Unless it is an interaction with a setting in the book.