Describes an interface that an Xtra can use to control its load/unload status.
An Xtra should register this interface using the normal technique (in IMoaRegister).
It can also register an additional long in its registry dict to request that it be preloaded at launch,
and/or that it never be unloaded once it is loaded.
With older versions of Director, this was an essential interface for resource based macintosh based Xtras.
Currently the kMoaXlc_PreloadAtLaunch option is still useful -
some asset xtras that also provide a global scripting method use the preload option.
As far as kMoaXlc_NeverUnload goes,
Xtra code libraries do not get unloaded so this setting is no longer useful.
Registry keys:
kMoaRegKey_XtraLoadControlOptions
kMoaRegType_XtraLoadControlOptions
Registry options:
kMoaXlc_PreloadAtLaunch
kMoaXlc_NeverUnload