ExpandableListTileButton class

A widget that provides an expandable list tile button with customizable headers and content.

The ExpandableListTileButton can be used to create a list tile that expands to reveal additional content when tapped. It supports custom headers, icons, expanded content, elevation for the combined widget, disabled state, and external control via ExpandableController.

Uses a Stack layout to ensure the header remains fully rounded and the body expands smoothly beneath it. Background colors for the header and expanded body areas are specified separately using headerBackgroundColor and expandedBodyColor. For backward compatibility, backgroundColor and expandedColor can also be used, but the newer names are preferred.

Example usage:

ExpandableController _controller = ExpandableController();
// ...
ExpandableListTileButton.listTile(
  controller: _controller,
  title: Text('Tap to expand'),
  expanded: Padding(
    padding: const EdgeInsets.all(16.0),
    child: Text('Expanded content goes here.'),
  ),
  margin: EdgeInsets.all(8),
  elevation: 4,
  headerBackgroundColor: Colors.blue[100], // Preferred
  expandedBodyColor: Colors.blue[50],    // Preferred
  borderRadius: BorderRadius.circular(12),
);