I got an outline error when working on the Stratego editor, when any edits to a Stratego file are made:

An internal error occurred during: "Updating outline view".

java.lang.IllegalStateException: Must be called from UI thread
	at org.strategoxt.imp.runtime.EditorState.getActiveEditor(EditorState.java:49)
	at org.strategoxt.imp.runtime.EditorState.getEditorFor(EditorState.java:79)
	at org.strategoxt.imp.runtime.services.views.outline.OutlineService.getOutline(OutlineService.java:42)
	at org.strategoxt.imp.runtime.services.views.outline.SpoofaxOutlinePage$2.run(SpoofaxOutlinePage.java:111)
	at org.eclipse.core.internal.jobs.Worker.run(Worker.java:53)

Using Spoofax 1.2.0.0-s41457.
Closing and opening the file is a workaround.

Submitted by Gabriël Konat on 7 May 2014 at 10:07

fixed https://github.com/metaborg/spoofax/commit/7b00f36ae9a6554727276d36e7f4d425e9904c0d