struct wxTreeViewItem;
// a callback function used for sorting tree items, it should return -1 if the
// first item precedes the second, +1 if the second precedes the first or 0 if
// they're equivalent
struct wxTreeViewItem;
// a callback function used for sorting tree items, it should return -1 if the
// first item precedes the second, +1 if the second precedes the first or 0 if
// they're equivalent