+
+ _start_position = TO_LEFT_OR_RIGHT_OF_VIEWBOX;
+ }
+
+ if (Keyboard::modifier_state_equals (ev->state, Keyboard::PrimaryModifier)) {
+
+ /* primary-modifier-click: start a zoom drag */
+
+ double const hx = (xr.first + xr.second) * 0.5;
+ _zoom_left = ev->x < hx;
+ _zoom_dragging = true;
+ _editor->_dragging_playhead = true;
+
+
+ /* In theory, we could support vertical dragging, which logically
+ might scale track heights in order to make the editor reflect
+ the dragged viewbox. However, having tried this:
+ a) it's hard to do
+ b) it's quite slow
+ c) it doesn't seem particularly useful, especially with the
+ limited height of the summary
+
+ So at the moment we don't support that...
+ */
+
+
+ } else if (Keyboard::modifier_state_equals (ev->state, Keyboard::SecondaryModifier)) {
+
+ /* secondary-modifier-click: locate playhead */
+ if (_session) {
+ _session->request_locate (ev->x / _x_scale + _start);
+ }
+
+ } else if (Keyboard::modifier_state_equals (ev->state, Keyboard::TertiaryModifier)) {
+