A function to be called to transform from_value to to_value. If
this is the transform_to function of a binding, then from_value
is the source_property on the source object, and to_value is the
target_property on the target object. If this is the
transform_from function of a G_BINDING_BIDIRECTIONAL binding,
then those roles are reversed.
A function to be called to transform from_value to to_value. If this is the transform_to function of a binding, then from_value is the source_property on the source object, and to_value is the target_property on the target object. If this is the transform_from function of a G_BINDING_BIDIRECTIONAL binding, then those roles are reversed.