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/src/org/eclipse/ui/internal/ide/misc/ResourceAndContainerGroup.java
* Gives focus to the resource name field and selects its contents
     */
    public void setFocus() {
        
        resourceNameField.setSelection(0, resourceNameField.getText().length());
        resourceNameField.setFocus();
    }
    /**
     * Sets the value of this page's resource name.
     *
     * @param value new value
     */
    public void setResource(String value) {
        resourceNameField.setText(value);
        validateControls();
    }
    /**
     * Returns a <code>boolean</code> indicating whether a container name represents
     * a valid container resource in the workbench.  An error message is stored for
     * future reference if the name does not represent a valid container.
     *
     * @return <code>boolean</code> indicating validity of the container name
     */
    protected boolean validateContainer() {
        IPath path = containerGroup.getContainerFullPath();
        if (path == null) {
            problemType = PROBLEM_CONTAINER_EMPTY;
            problemMessage = IDEWorkbenchMessages.ResourceGroup_folderEmpty;
            return false;
        }