Q: The sorting gui disappeared, where is it?
A: This can have multiple causes.

• You closed a gui and the state of the now current gui can not be determined.
  Close and reopen the object.
• The foreground gui may be bigger now (mods,scaling,etc).
  Move the foreground gui around to see if the sorting gui is hidden behind it.
• Changes to screen resolution or scaling may have pushed the sorting gui outside the screen.
  Open the console (usually "^", top left of your keyboard below "ESC") and enter the command "/sortme reset".

Q: Your sorting order sucks, can we have some alternatives please?
A: Since inventories (and books also count as inventories) have their integrated sort_and_merge function, i am somewhat reluctant to build my own.
My sorting functions also try to create the same order as the crafting menu, item select menu and inventories.
If you think you have a better sorting order, try to convince me in the discussions.

Q: Can you please also sort X?
A: That is absolutely definitively a maybe.
While my mod should handle everything vanilla factorio has to offer, i can't promise that i did not overlook anything.
But factorio gives modders a whole toolbox with goodies to play shenanigans with. So i am sure there are some mods out there with stuff i could sort.
If you find such a mod, request a sort button and i add it if i can.

Q: I got the message that your mod is malfunctioning. What does that mean?
A: Instead of halting the game my mod tries to "gracefully" ignore errors. If this happens only once and you have no idea why, you can probably ignore that. But i would be happy if you filed a bug report regardless.
If that message is a regular occurrence you should definitely write a bug report, because you or a mod you use does something i have not accounted for. or i forgot something.

Q: Fine, i'll write you a bug report. What do you need?
A: A description of the error, preferably with exact steps to reproduce, be as detailed as possible please.