+ bool dragging;
+ double drag_start_pos;
+ double drag_start_value;
+ unsigned drag_area_size;
+ unsigned drag_area_offset;
+ unsigned slider_size;
+
+ Slider();
+
+public:
+ void set_value(double);
+ void set_range(double, double);
+ void set_step(double);
+ double get_value() const { return value; }
+
+protected:
+ void click(int);
+ void start_drag(int);
+ void drag(int);
+ void end_drag();