- if (fabs (accumulated_delta) >= 0.025) {
- width_control->set_value (current_width + accumulated_delta);
- detented = false;
- accumulated_delta = false;
+ /* maintain position as invariant as we change the width */
+
+ /* create a detent close to the center */
+
+ if (!detented && fabs (current_width) < 0.02) {
+ detented = true;
+ /* snap to zero */
+ width_control->set_value (0);
+ }
+
+ if (detented) {
+
+ accumulated_delta += delta;
+
+ /* have we pulled far enough to escape ? */
+
+ if (fabs (accumulated_delta) >= 0.025) {
+ width_control->set_value (current_width + accumulated_delta);
+ detented = false;
+ accumulated_delta = false;
+ }
+
+ } else {
+ /* width needs to change by 2 * delta because both L & R move */
+ width_control->set_value (current_width + (delta * 2.0));