Eclipse IDE for C/C++ Developers
Version: Neon.2 Release (4.6.2)
Windows 10 with 200% scaling (192 dpi)

Steps to replicate :

1. Create a C++ project
2. Right click on the project > Properties > C/C++ General -> Preprocessor Include Paths -> GNU C++
3. Expand tree for Sync CC Built-in Compiler Settings
4. The arrow indicating the subtree reverts to a black arrow and a native horizontal scrollbar appears at the bottom. Clicking on any item seems to have no effect including the vertical scrollbar. The window is in a frozen state until we close it.