expand method

void expand()

Expands the bar.

Always allowed, whatever the behaviour — expanding can only restore the default state. Wire this to onMinimizedTabTap so the "bring my tabs back" tap and the scroll state machine agree; otherwise the tap would clear the app's flag while this controller still believed the bar was minimized, and the next downward scroll would appear to do nothing.

Implementation

void expand() {
  _accumulated = 0.0;
  _setMinimized(false);
}