struct PreviewImage::Impl : public boost::signals::trackable {
///
Impl(PreviewImage & p, PreviewLoader & l,
string const & s, string const & f, double af);
///
struct PreviewImage::Impl : public boost::signals::trackable {
///
Impl(PreviewImage & p, PreviewLoader & l,
string const & s, string const & f, double af);
///