float blink = (sinf(real_time * M_PI * 1.0f)/2.0f + 0.5f) * 0.5f + 0.25f;
ctx.draw_filled_rect(Rectf(Vector(pos.x - button_width/2, pos.y - button_height/2),
Vector(pos.x + button_width/2, pos.y + button_height/2)).grown(2.0f),
float blink = (sinf(real_time * M_PI * 1.0f)/2.0f + 0.5f) * 0.5f + 0.25f;
ctx.draw_filled_rect(Rectf(Vector(pos.x - button_width/2, pos.y - button_height/2),
Vector(pos.x + button_width/2, pos.y + button_height/2)).grown(2.0f),