Bug 113239 new compiler option 'fatalOptionalError'
* COMPILER / Treating Optional Error as Fatal * When enabled, optional errors (i.e. optional problems which severity is set to "error") will be treated as standard * compiler errors, yielding problem methods/types preventing from running offending code until the issue got resolved. * When disabled, optional errors are only considered as warnings, still carrying an error indication to make them more * severe. Note that by default, errors are fatal, whether they are optional or not. * - option id: "org.eclipse.jdt.core.compiler.problem.fatalOptionalError" * - possible values: { "enabled", "disabled" } * - default: "enabled" </pre>
org.eclipse.jdt.ui/ui/org/eclipse/jdt/internal/ui/preferences/JavaBuildConfigurationBlock.java
* Update fields and validate.
	 * @param changedKey Key that changed, or null, if all changed.
	 */	
	protected void validateSettings(Key changedKey, String oldValue, String newValue) {
		if (!areSettingsEnabled()) {
			return;
		}
		
		if (changedKey != null) {
			if (PREF_PB_MAX_PER_UNIT.equals(changedKey)) {
				fMaxNumberProblemsStatus= validateMaxNumberProblems();
			} else if (PREF_RESOURCE_FILTER.equals(changedKey)) {
				fResourceFilterStatus= validateResourceFilters();
			} else {
				return;
			}
		} else {
			updateEnableStates();
			fMaxNumberProblemsStatus= validateMaxNumberProblems();
			fResourceFilterStatus= validateResourceFilters();
		}		
		IStatus status= StatusUtil.getMostSevere(new IStatus[] { fMaxNumberProblemsStatus, fResourceFilterStatus });
		fContext.statusChanged(status);
	}
	
	private void updateEnableStates() {
	}
	
	protected String[] getFullBuildDialogStrings(boolean workspaceSettings) {
		String title= PreferencesMessages.JavaBuildConfigurationBlock_needsbuild_title;