In fact OpenMSX is reading all : keysym.sym, keysym.mod,keysym.scancode and keysym.unicode.
After a comparison, with HF6 SDL, i get :
F10 : Unicode 0X0000, Keycode0x400123, KeyName F10
F11 : Unicode 0X0000, Keycode0x400124, KeyName F11
And with this SDL :
F10 : Unicode 0X0000...