freeze when running imGUI demo on sdl2 in console (KMSDRM)

I want to create a GUI that can run both in console or in X11,
the GUI use imGUI opengl widgets GitHub - ocornut/imgui: Dear ImGui: Bloat-free Graphical User interface for C++ with minimal dependencies
the sdl2 is built with kmsdrv driver
to test the app, I used the example app of imgui (imgui/examples/example_sdl2_opengl2 at master · ocornut/imgui · GitHub)

on x11, nothing to say, the example app is working as expected
on console, the app launch, there is the demo app displayed, but after, system seems to freeze, ctrl+alt+Fx don’t allow anymore to cycle through consoles, mouse don’t move…

I don’t know how to debug the issue…
any idea?
thanks and regards