You may need to activate it through the dfhack tab.
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No idea on DT, sadly. For TwbT, open either launcher and go to the last tab - then ensure multilevel is turned on.
I'm guessing he is using the graphics pack that comes with the starter pack as the default one which is just the regular phoebus version with 2D set as the print mode instead of the twbt version in the LNP\graphics section with the correct twbt stuff/init.
Edit: The overrides that come in the graphics packs are pretty much blank and make it so there are no weapon or item overrides if you use the PyLNP launcher but the old launcher doesn't overwrite the overrides still so those who used that are lucky.
For some reason there are .bak files when using the PyLNP launcher. d_init, init, inorganic_stone_layer.txt, mineral/soil. Interestingly enough the backups are the same as the regular txt files (they won't be loaded by dwarf fortress). The old launcher doesn't have this problem when tested on the 40.13 version. Also seems to do it when just loading up the PyLNP launcher.
It's also a bit annoying how the launchers default to the 120 pop cap, 100/50 fps cap, 100:1000 baby cap and change the loaded d_init/init to the values it wants.
The old launcher is having a opposite day party where the entombed pets setting is saying the opposite of what it is actually set to.
All graphics packs have TwbT enabled, but the multilevel view has to be truned on through the dfhack tab - this seems be causing issues, so next pack it'll just be on through dfhack.init
I'll fix the overrides issue, I must have added the basic one instead of Meph's version. Use of specific overrides on a per-graphics-pack basis is coming, but will have to wait for the old launcher to be phased out (it can't do this).
The launchers should both preserve any non-graphical settings when installing a graphics pack. Is something else happening?
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Basically we want to keep the launcher generally useful, so assuming the presence of TwbT is out and it's not so mature yet that we have logic to check for everything. Even then, the dfhack list is customised through the config file so we'd need some crazy checking for special cases and a way to define all the particular behaviour, to the point where it'd be a lot easier just to fork the launcher each time. The printmode setting also has many more effects than just TwbT - Rendermax, Stonesense, other graphics, Truetype, stability... if you have a better idea for the tooltip it'd be great to hear.