@Lindon If you set the current expansion to "" that will trigger the unload action, so you can respond to that. I'm not sure if that reruns the player's on init but you could test.

I think a timer and polling on the message thread is the way to go, the timer won't run when the interface is minimised anyway.

Yeah its the expansion that will be setting the current expansion to "" - so I'm not sure how the player responds to that....I cant see a expansion changed callback or listener...

I think a timer and polling on the message thread is the way to go, the timer won't run when the interface is minimised anyway.

@David-Healey state is simply "open" or "closed" (0 or 1) for every library (which has categories in it) and Categories(which have instruments in them)

State needs to be transferable BOTH ways so we start with all libs closed....

In the player we open LibA, open CatA and load InstrumentAA

InstrumentAA opens and displays the LibPanel with all libs closed except LibA, and within that CatA is also open...

In instrumentAA we close LibA and Open LibB, then we close InstrumentAA,

The player opens with all libs closed except LibB

The problem(well theres a truck load of problems..) here is I can see how I can save state (in some file) and read it on plugin(player) load...and as soon as the user requests a load of an instrument we write the current states to the file.

The instrument reads this state file on load and sets the display correctly. On instrument unload (so the instrument is unloading itself) the instrument saves the new state(assuming its changed) and unloads itself.....

..but I dont know how the player now reads this new state file in any efficient manner- meaning not running a timer every 0.5 seconds to re-read the state file......???

The player never knows the instrument is now unloaded does it? Or can it tell from

ExpansionHandler.getCurrentExpansion() if it == "" then whatever it loaded is now unloaded... ???

Or how is the player itself loading/unloading whilst a Full Instrument is in play? I guess I need to know the mechanics of player/instrument load/unload ....do we execute init again? ...@Christoph-Hart !!!

State needs to be transferable BOTH ways so we start with all libs closed....

In the player we open LibA, open CatA and load InstrumentAA

InstrumentAA opens and displays the LibPanel with all libs closed except LibA, and within that CatA is also open...

In instrumentAA we close LibA and Open LibB, then we close InstrumentAA,

The player opens with all libs closed except LibB