Bug 81983 [preferences] Disabling and enabling folding on small file takes forever
3.1 M4 Using enable/disable folding on a small CU takes forever. This is caused by the recent change to apply the preference to all Java editors. In another (hidden) window (Debug) I had StyledText open which (understandably) took long to react on the preference change. Non-visible editor's should not react to this change until they become visible.
org.eclipse.jdt.ui/ui/org/eclipse/jdt/internal/ui/javaeditor/JavaEditor.java
}
	/*
	 * @see org.eclipse.ui.IWorkbenchPart#createPartControl(org.eclipse.swt.widgets.Composite)
	 */
	public void createPartControl(Composite parent) {
		super.createPartControl(parent);
		ProjectionViewer projectionViewer= (ProjectionViewer) getSourceViewer();
		
		fProjectionSupport= new ProjectionSupport(projectionViewer, getAnnotationAccess(), getSharedColors());
		fProjectionSupport.addSummarizableAnnotationType("org.eclipse.ui.workbench.texteditor.error"); 
		fProjectionSupport.addSummarizableAnnotationType("org.eclipse.ui.workbench.texteditor.warning"); 
		fProjectionSupport.setHoverControlCreator(new IInformationControlCreator() {
			public IInformationControl createInformationControl(Shell shell) {
				return new CustomSourceInformationControl(shell, IDocument.DEFAULT_CONTENT_TYPE);
			}
		});
		fProjectionSupport.install();
		
		fProjectionModelUpdater= JavaPlugin.getDefault().getFoldingStructureProviderRegistry().getCurrentFoldingProvider();
		if (fProjectionModelUpdater != null)
			fProjectionModelUpdater.install(this, projectionViewer);
				
		if (isFoldingEnabled())
			projectionViewer.doOperation(ProjectionViewer.TOGGLE);
		
		IInformationControlCreator informationControlCreator= new IInformationControlCreator() {
			public IInformationControl createInformationControl(Shell shell) {
				boolean cutDown= false;
				int style= cutDown ? SWT.NONE : (SWT.V_SCROLL | SWT.H_SCROLL);
				return new DefaultInformationControl(shell, SWT.RESIZE, style, new HTMLTextPresenter(cutDown));