Bug 134740 [Wizards] PDE product wizard is not obvious to use.
see attached image. The wizard for creating a new product opens with a file name initialized to ".product" which is selected. Generally this would imply that this is a good default but if you start typing you will replace the text with something else that is also a good name. If you require an extension for a file you should add it yourself like the "Export Archive" wizard.
bundles/org.eclipse.ui.ide/extensions/org/eclipse/ui/dialogs/WizardNewFileCreationPage.java
setErrorMessage(status.getMessage());
			}
		} else if (status.getSeverity() == IStatus.WARNING) {
			setMessage(status.getMessage(), WARNING);
			setErrorMessage(null);
		}
		return status;
	}
	/**
	 * Returns whether this page's controls currently all contain valid values.
	 * 
	 * @return <code>true</code> if all controls are valid, and
	 *         <code>false</code> if at least one is invalid
	 */
	protected boolean validatePage() {
		boolean valid = true;
		if (!resourceGroup.areAllValuesValid()) {
			
			if (resourceGroup.getProblemType() == ResourceAndContainerGroup.PROBLEM_RESOURCE_EMPTY
					|| resourceGroup.getProblemType() == ResourceAndContainerGroup.PROBLEM_CONTAINER_EMPTY) {
				setMessage(resourceGroup.getProblemMessage());
				setErrorMessage(null);
			} else {
				setErrorMessage(resourceGroup.getProblemMessage());
			}
			valid = false;
		}
		String resourceName = resourceGroup.getResource();
		IWorkspace workspace = ResourcesPlugin.getWorkspace();
		IStatus result = workspace.validateName(resourceName, IResource.FILE);