I have got working a basic file explorer in UTF8. It is not ready to use but maybe someone wants to keep an eye on it.
You can find the source code at
GitHub, forked from jenGs's repository, all my functions are included in two new files: imgui_dll_fonts.cpp and imgui_dll_helpers.cpp.
The main work has been around a function that prepares the folder data to be shown in an imgui list box: an array of char*. I tried different methods and finally ended up with a function that fills a buffer owned by the caller instead of the dynamic allocation I tried first, so at the end it can happen that the folder content names are longer that the space available and will result in a clipped content list. I do all the stuff with experimental::filesystem. The function can inject a prefix to folders. In the example I used one of the private ucodes (E800-E8FF) to show that folder icon I inserted into the ttf file (with Type Light).
The file explorer behaviour is in liteC with the help of some helper functions included in the dll. It desplegates a combo in root drives and a button per folder in the path. It rebuilds the data when clicking over a subfolder and activates the selection button when clicking over a file.
The fonts implementation is pretty choppy. I have no idea how to easily implement the custom glyph ranges.