Having expanding/expanded events has been confusing in the past -- we prefer introducing events that are cancellable (expanding) and different events that get called afterwards (like the "activated" event that is fired when the window widget is opened). In your case, you should be able to check the pane state when the splitter is redrawn by attaching an event handler to the resize
Another workaround that usually works is to place the code in a setTimeout function that delays the execution -- but it isn't as pretty as using the proper event.
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