+/** @return true if b is a non-zero pointer and the bundle it points to has some channels */
+bool
+PortMatrix::bundle_with_channels (boost::shared_ptr<ARDOUR::Bundle> b)
+{
+ return b && b->nchannels() != ARDOUR::ChanCount::ZERO;
+}
+
+/** See if a `flip' is possible.
+ * @return If flip is possible, the new (row, column) notebook indices that
+ * should be selected; otherwise, (-1, -1)
+ */
+pair<int, int>
+PortMatrix::check_flip () const
+{
+ /* Look for the row's port group name in the columns */
+
+ int new_column = 0;
+ boost::shared_ptr<const PortGroup> r = visible_ports (_row_index);
+ PortGroupList::List::const_iterator i = _ports[_column_index].begin();
+ while (i != _ports[_column_index].end() && (*i)->name != r->name) {
+ ++i;
+ ++new_column;
+ }
+
+ if (i == _ports[_column_index].end ()) {
+ return make_pair (-1, -1);
+ }
+
+ /* Look for the column's port group name in the rows */
+
+ int new_row = 0;
+ boost::shared_ptr<const PortGroup> c = visible_ports (_column_index);
+ i = _ports[_row_index].begin();
+ while (i != _ports[_row_index].end() && (*i)->name != c->name) {
+ ++i;
+ ++new_row;
+ }
+
+ if (i == _ports[_row_index].end ()) {
+ return make_pair (-1, -1);
+ }
+
+ if (_arrangement == LEFT_TO_BOTTOM) {
+ new_row = _ports[_row_index].size() - new_row - 1;
+ }
+
+ return make_pair (new_row, new_column);
+}
+
+bool
+PortMatrix::can_flip () const
+{
+ return check_flip().first != -1;
+}
+
+/** Flip the column and row pages around, if possible */
+void
+PortMatrix::flip ()
+{
+ pair<int, int> n = check_flip ();
+ if (n.first == -1) {
+ return;
+ }
+
+ _vnotebook.set_current_page (n.first);
+ _hnotebook.set_current_page (n.second);
+}
+
+bool
+PortMatrix::key_press (GdkEventKey* k)
+{
+ if (k->keyval == GDK_f) {
+ flip ();
+ return true;
+ }
+
+ return false;
+}