Maybe you are using outdated SFML2 version? Download sfml2 current sources and compile it using:
Also make sure you use the same commands to compile tgui.
(just a guess, I never encountered something like that with tgui on linux)
Code Select
cmake .
make
sudo make install
Also make sure you use the same commands to compile tgui.
(just a guess, I never encountered something like that with tgui on linux)