NappDrawer back button capture. This sample closes the sidebar.

gistfile1.md

You could accomplish this yourself. Add an event listener to watch for the android back button pressed. Here is a code sample that should accomplish this. There are two event listeners because Android emits different events depending on the version. See docs.

$.drawer.window.addEventListener('android:back', androidBackPressed);
$.drawer.window.addEventListener('androidback', androidBackPressed);

function androidBackPressed() {
  if ($.drawer.isLeftWindowOpen) {
    $.drawer.toggleLeftWindow();
  }
}