[Bug]: Airport menu selectability after closing window on a class with no available airports

[PikkaBird]

Version of OpenTTD

20230903-master-gdadf5182d8

Expected result

If you close the airport construction menu while on a class tab with no buildable airports, on reopening the menu it reverts to displaying "Small Airports" [presumably the first available class with buildable airports].

Actual result

However, as seen in the example below with opengfx+ airports, on reopening the window only the first two airports in the list are selectable. The "Vintage Commuter" airport is not selectable, until clicking on the "class" dropdown and reselecting "small airports".

[Presumably this is because there's a counter that is not reset properly when resetting the class to display on reopening the window - it only allows selecting as many "Small Airports" as there are "Hub Airports"].

Steps to reproduce

1. Start a new game in 1950 with the OpenGFX+ Airports NewGRF with default parameters.
2. Open the Airport Construction window and change the class to "Hub Airports".
3. Close and reopen the Airport Construction window. It will have defaulted back to "Small Airports".
4. Note how you cannot select "Vintage Commuter" until you click and reselect "Small Airports" at the top of the window.