ementById("solver_2");
    var canvas_rect = solver.getBoundingClientRect();
    draw_solver_2(0, 0, false);

    solver.addEventListener('mousemove', function(e){
        var canvas_rect = solver.getBoundingClientRect();
        draw_solver_2(e.clientX - canvas_rect.left, e.clientY - canvas_rect.top, true);
        if(e.buttons == 1) {
            invalidate_solver_2(e.clientX, e.clientY);
        } else if(e.buttons == 0) {
            solver_2_eq_temp_id = find_nearest_eqution_id("solver_2", e.clientX - 