Hi Mirek,
Sorry to take this long to get back helping with this, but hopefully back from the dead, or at least nothing drugs can't fix.

I forked the u++ and selected animation branch , then edited the assembly to point to the cloned fork.
after trying to compile that I'm getting an error with the tabbar

E:\github\ultimatepp\uppsrc\TabBar\TabBar.cpp (936): error: call to non-static member function without an object argument
.. ChPaint(w, isz, v);
a little hack of Upp::ChPaint(w, isz, v); (was a static define)

but unfortunately I'm now getting some linking errors ():

(): Linking has failed
(): ld.lld: error: undefined symbol: WspiapiGetNameInfo
(): >>> referenced by libcrypto.a(libcrypto-lib-bio_addr.obj):(addr_strings)
():
(): ld.lld: error: undefined symbol: gai_strerrorA
(): >>> referenced by libcrypto.a(libcrypto-lib-bio_addr.obj):(addr_strings)
(): >>> referenced by libcrypto.a(libcrypto-lib-bio_addr.obj):(BIO_lookup_ex)
():
(): ld.lld: error: undefined symbol: WspiapiFreeAddrInfo
(): >>> referenced by libcrypto.a(libcrypto-lib-bio_addr.obj):(BIO_ADDRINFO_free)
():
...

seems these are windows libs , I loaded the SDK and added the lines -lcrypt32 -ladvapi32 -lWs2_32 -lMswsock to the common link options
but there still seems to be a issue finding the correct things, not sure what im missing here.
... this is why building projects freaks me out..lol

PS: I realize you're quite busy but would it be possible to create a new branch off the main with these animation adjustments?
i tested a merge but \Core\Map.hpp conflict so not sure if this would break the latest branch??