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
} else if (object instanceof IAdaptable) {
					selectedResource = (IResource) ((IAdaptable) object)
							.getAdapter(IResource.class);
				}
				if (selectedResource != null) {
					if (selectedResource.getType() == IResource.FILE) {
						selectedResource = selectedResource.getParent();
					}
					if (selectedResource.isAccessible()) {
						resourceGroup.setContainerFullPath(selectedResource
								.getFullPath());
					}
				}
			}
		}
	}
	/**
	 * Sets the value of this page's container name field, or stores it for
	 * future use if this page's controls do not exist yet.
	 * 
	 * @param path
	 *            the full path to the container
	 */
	public void setContainerFullPath(IPath path) {
		if (resourceGroup == null) {
			initialContainerFullPath = path;
		} else {
			resourceGroup.setContainerFullPath(path);
		}
	}