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
if (javaProject == null)
						return true;
					
					return !javaProject.getProject().equals(event.getSource());
				}
				
			}));
		
		stores.add(JavaPlugin.getDefault().getPreferenceStore());
		stores.add(new PreferencesAdapter(JavaCore.getPlugin().getPluginPreferences()));
		stores.add(EditorsUI.getPreferenceStore());
		
		return new ChainedPreferenceStore((IPreferenceStore[]) stores.toArray(new IPreferenceStore[stores.size()]));
	}
	/**
	 * Sets the outliner's context menu ID.
	 * 
	 * @param menuId the menu ID 
	 */
	protected void setOutlinerContextMenuId(String menuId) {
		fOutlinerContextMenuId= menuId;
	}
			
	/**
	 * Returns the standard action group of this editor.
	 * 
	 * @return returns this editor's standard action group 
	 */
	protected ActionGroup getActionGroup() {
		return fActionGroups;