Should fix tilde/grave key.

input/x11_input.c

@@ -65,6 +65,7 @@ static const struct key_bind lut_binds[] = {
    { XK_KP_Subtract, SDLK_KP_MINUS },
    { XK_KP_Multiply, SDLK_KP_MULTIPLY },
    { XK_KP_Divide, SDLK_KP_DIVIDE },
+   { XK_grave, SDLK_BACKQUOTE },
    { XK_KP_0, SDLK_KP0 },
    { XK_KP_1, SDLK_KP1 },
    { XK_KP_2, SDLK_KP2 },

settings.c

@@ -642,6 +642,7 @@ static const struct key_map sdlk_map[] = {
    { "divide", SDLK_KP_DIVIDE },
    { "print_screen", SDLK_PRINT },
    { "scroll_lock", SDLK_SCROLLOCK },
+   { "tilde", SDLK_BACKQUOTE },
    { "nul", SDLK_UNKNOWN },
 };