Fossil

     Returns F.toast.
  */
  const toastImpl = function f(cssClass, durationMult, argsObject){
    if(!f.toaster){
      f.toaster = new F.PopupWidget({
        cssClass: 'fossil-toast-message'
      });
      D.attr(f.toaster.e, 'role', 'alert');
    }
    const T = f.toaster;
    if(f._timer) clearTimeout(f._timer);
    D.clearElement(T.e);
    if(f._prevCssClass) T.e.classList.remove(f._prevCssClass);
    if(cssClass) T.e.classList.add(cssClass);
    f._prevCssClass = cssClass;

  F.toast = {
    config: {
      position: { x: 5, y: 5 /*viewport-relative, pixels*/ },
      displayTimeMs: 3000
    },
    /**
       Convenience wrapper around a PopupWidget which pops up a shared
       PopupWidget instance to show toast-style messages (commonly seen
       on Android). Its arguments may be anything suitable for passing
       to fossil.dom.append(), and each argument is first append()ed to
       the toast widget, then the widget is shown for
       F.toast.config.displayTimeMs milliseconds. This is called while
       a toast is currently being displayed, the first will be overwritten
       and the time until the message is hidden will be reset.
       PopupWidget instance to show toast-style messages (commonly
       seen on Android). Its arguments may be anything suitable for
       passing to fossil.dom.append(), and each argument is first
       append()ed to the toast widget, then the widget is shown for
       F.toast.config.displayTimeMs milliseconds. If this is called
       while a toast is currently being displayed, the first will be
       overwritten and the time until the message is hidden will be
       reset.

       The toast is always shown at the viewport-relative coordinates
       defined by the F.toast.config.position.

       The toaster's DOM element has the CSS classes fossil-tooltip
       and fossil-toast, so can be style via those.
       The toaster's DOM element has the CSS class fossil-tooltip
       and fossil-toast-message, so can be style via those.

       The 3 main message types (message, warning, error) each get a
       CSS class with that same name added to them. Thus CSS can
       select on .fossil-toast-message.error to style error toasts.
    */
    message: function(/*...*/){
      return toastImpl(false,1, arguments);
    },
    /**
       Displays a toast with the 'warning' CSS class assigned to it. It
       displays for 1.5 times as long as a normal toast.