I had more time to do some toying around, and here's a simple solution. I believe the flight paths are already marked, just invisible and changed to a different icon. They appear briefly when you mouse over other paths, if it requires going past a location you haven't discovered.
So the solution is just to make them appear, and stop the game from re-hiding them.
Lua Code:
-- Step 1: Wait for the flight map to be created
-- Step 2: Any time the flight map appears, enumerate through every flight path pin
-- Step 3: Make each pin shown, and prevent the the OnMouseEnter/OnMouseLeave events from overriding this
-- STEP 1:
local alreadyHooked
hooksecurefunc("FlightMap_LoadUI", function()
if (alreadyHooked) then
return
else
alreadyHooked = true
-- STEP 2:
FlightMapFrame:HookScript("OnShow", function()
for pin in FlightMapFrame:EnumeratePinsByTemplate("FlightMap_FlightPointPinTemplate") do
-- STEP 3:
pin:Show()
pin.SetShown = pin.Show
end
end)
end
end)
PS. This is the complete addon, minus the TOC file of course. I tested briefly with an alt who had a couple unknown flight paths and it seemed to work.