code: protected boolean validatePage() {
  		setMessage(null);
  		setErrorMessage(null);
  
  		if (!super.validatePage()) {
  			return false;
  		}
  
  		String fileName = getFileName();
  		IPath fullPath = getContainerFullPath();
  		if ((fullPath != null) && (fullPath.isEmpty() == false) && (fileName != null)) {
  			// check that filename does not contain invalid extension
  			if (!extensionValidForContentType(fileName)) {
  				setErrorMessage("Filename must end with .card");
  				return false;
  			}
  			// no file extension specified so check adding default
  			// extension doesn't equal a file that already exists
  			if (fileName.lastIndexOf('.') == -1) {
  				String newFileName = addDefaultExtension(fileName);
  				IPath resourcePath = fullPath.append(newFileName);
  
  				IWorkspace workspace = ResourcesPlugin.getWorkspace();
  				IStatus result = workspace.validatePath(resourcePath.toString(), IResource.FOLDER);
  				if (!result.isOK()) {
  					// path invalid
  					setErrorMessage(result.getMessage());
  					return false;
  				}
  
  				if ((workspace.getRoot().getFolder(resourcePath).exists() || workspace.getRoot().getFile(resourcePath).exists())) {
  					setErrorMessage("There is a card with that name");
  					return false;
  				}
  			}
  
  			// get the IProject for the selection path
  			IProject project = getProjectFromPath(fullPath);
  			// if inside web project, check if inside webContent folder
  			if (project != null && isWebProject(project)) {
  				// check that the path is inside the webContent folder
  				IPath[] webContentPaths = ProjectUtils.getAcceptableRootPaths(project);
  				boolean isPrefix = false;
  				for (int i = 0; !isPrefix && i < webContentPaths.length; i++) {
  					isPrefix |= webContentPaths[i].isPrefixOf(fullPath);
  				}
  				if (!isPrefix) {
  					setMessage("Cards must be inside the web contents", WARNING);
  				}
  			}
  		}
  
  		return true;
  	}
docs: This method is overridden to set additional validation specific to html
  files.