Bug 123989 Should ResourceChangeValidator#validateChange take a progress monitor
Since the validation might take some time it might make sense to pass a progress monitor into validateChange.
bundles/org.eclipse.ui.ide/src/org/eclipse/ui/ide/IDE.java
/**
	 * Guess at the content type of the given file based on the filename.
	 * 
	 * @param file the file to test
	 * @return the content type, or <code>null</code> if it cannot be determined.
	 * @since 3.2
	 */
	public static IContentType guessContentType(IFile file) {
		String fileName = file.getName();
		try {
			UIStats.start(UIStats.CONTENT_TYPE_LOOKUP, fileName);
			IContentTypeMatcher matcher = file.getProject().getContentTypeMatcher();
			return matcher.findContentTypeFor(fileName);
		} catch (CoreException e) {
			return null;		
		} finally {
			UIStats.end(UIStats.CONTENT_TYPE_LOOKUP, file, fileName);
		}
	}
	
    /**
     * Prompt the user to inform them of the possible side effects
     * of an operation on resources. Do not prompt for side effects 
     * from ignored model providers. A model provider can be ignored if
     * it is the client calling this API. Any message from the provided
     * model provider id or any model providers it extends will be ignored. 
     * @param shell the shell to parent the prompt dialog
     * @param title the title of the dialog
     * @param message the message for the dialog
     * @param delta a delta built ising an <code>IProposedResourceDeltaFactory</code>