-static char *interpret_move(game_state *state, game_ui *ui, game_drawstate *ds,
+static char *interpret_move(game_state *state, game_ui *ui, const game_drawstate *ds,
int x, int y, int button)
{
int w = state->p.w, h = state->p.h;
int x, int y, int button)
{
int w = state->p.w, h = state->p.h;