Provides a dynamic interface for properties which cannot be represented
with simple strings, e.g. pictures. The keys of such properties can
be queried using `complexPropertyKeys()`, which could return for example
["PICTURE"]. The property can then be read using
`complexProperties("PICTURE")`, which will return a list of variant maps
containing the picture data and attributes. Adding a picture is as
easy as
t->setComplexProperties("PICTURE", {
{
{"data", data},
{"pictureType", "Front Cover"},
{"mimeType", "image/jpeg"}
}
});
6be03b7ae1