(Draft because I still have others things planned for tonight, but wanted to braindump a few things first)

Namely, AFAICT, the nextTick nastiness in reader.lua (from all the way back to #1877) is completely unnecessary, as #1988 enforced a repaint after the popup in question, and that has no bearing on the state of the main loop, it will repaint now.

I Just debugged this, (I had suspected that commit) and came to comment when i saw this :)

My fix was just to add a line:

    self._exit_code = nil

to the beginning of UIManager:run() without the whole run once function

it is the self._exit_code being leaked across runs of UIManager

Yup! I'd rather be overly explicit to document this and avoid a future regression if we lost this to the sands of time, though ;).

(And also to actually skip the :quit() call, because it might not always stay as mostly harmless as it is today).

Namely, AFAICT, the nextTick nastiness in reader.lua (from all the way back to #1877) is completely unnecessary, as #1988 enforced a repaint after the popup in question, and that has no bearing on the state of the main loop, it will repaint now.

Confirmed when testing the Kindle stuff on a slow PW1: it works just fine.

Kindle t1 timeout trickery seems to behave, yay.

ReaderHighlight: Appease newer versions of LuaCheck
Good to know: it now defaults to assuming that anything
prefixed with an underscore would be unused, which is... nice in theory ;).

Well, does that mean it won't complain when we have unused:

local _ = require("gettext")
local _mirroredUI = BD.mirroredUILayout()
local _start_seg = end_seg + icon_sep_width

But mhhh, what does it complain about if it can assume they are unused ? :)

ReaderHighlight: Appease newer versions of LuaCheck
Good to know: it now defaults to assuming that anything
prefixed with an underscore would be unused, which is... nice in theory ;).

Well, does that mean it won't complain when we have unused:

local _ = require("gettext")
local _mirroredUI = BD.mirroredUILayout()
local _start_seg = end_seg + icon_sep_width

But mhhh, what does it complain about if it can assume they are unused ? :)

Weeeeell, I have no idea what's happening then :D.

Checking foo.lua                                  5 warnings

    foo.lua:2:7-17: (W211) unused variable _mirroredUI
    foo.lua:2:21-22: (W113) accessing undefined variable BD
    foo.lua:3:7-16: (W211) unused variable _start_seg
    foo.lua:3:20-26: (W113) accessing undefined variable end_seg
    foo.lua:3:30-43: (W113) accessing undefined variable icon_sep_width

Total: 5 warnings / 0 errors in 4 files

Weeeeell, I have no idea what's happening then :D.

Mystery solved: it's when function arguments are prefixed.

local function foo(_bar, baz)
        return _bar + baz
end

Checking foo.lua                                  2 warnings

    foo.lua:1:16-18: (W211) unused function foo
    foo.lua:1:20-23: (W214) used variable _bar with unused hint

Total: 2 warnings / 0 errors in 4 files