[DahkCeles]

Further testing: underwater nodes in Vashj'ir do not play nice with above-water nodes in the Eastern Kingdoms. A few extra lines of code can solve that problem...

-- Step 1: Wait for the flight map to be created
-- Step 2: Any time the flight map appears, enumerate through every flight path pin and do steps 3 and 4 at least once
-- Step 3: Make each pin shown, and prevent the the OnMouseEnter/OnMouseLeave events from overriding this
-- Step 4: Undersea nodes in Vashj'ir will not play nice, so override the click handler
-- Step 5: Also because of Vashj'ir, change the tooltip text just a little
 
 
-- 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
                if (pin.alreadyHooked == nil) then
                    pin.alreadyHooked = true
                    -- STEP 3:
                    pin:Show()
                    pin.SetShown = pin.Show
                    -- STEP 4:
                    function pin:OnClick(button)
                        if button == "LeftButton" and self.taxiNodeData.state == Enum.FlightPathState.Reachable then
                            TakeTaxiNode(self.taxiNodeData.slotIndex);
                        end
                    end
                end
            end
        end)
    end
end)
 
 
-- Instead of saying 'not discovered' it will say 'not available'
TAXI_PATH_UNREACHABLE = ADDON_NOT_AVAILABLE

You are correct about Draenor. Here's the source code for that one:
https://www.townlong-yak.com/framexm...xiFrame.lua#32