TOPIC: Compiling OpenTTD 1.9.1 BTPRO client on Mac OSX 10.14.3

After getting it to work on my old laptop as described in this topic , I experienced some choppiness (14 year old hardware, who knew!).

I decided to give it a spin on my Mac Mini (2014).

Compiling went fine, I used the guides on www.openttd.org . And I used home-brew to get the required dependencies. After successfully applying the .diff file, with 'patch -p1 < ...' and compiling the bundle, I tried running the game.
Unfortunately it reported 'cannot find innerhighlight.grf' on startup and would not run.

Finally I figured out the 'innerhighlight.grf' file needs to go into the .app package under 'Contents/Resources/baseset':
Right-click the OpenTTD app/executable and select 'Show package contents', which opens up Finder. Copy the the .grf file to the location as described above.

After which the game with BTPRO interface worked like a charm!