pages, White pages, Stocks, and a City guide, all integrated into menu-enabled toolbar buttons. Furthermore, a webmail button is included in the toolbar, which links directly to multiple webmail homepages and is configurable for multiple webmail accounts. A button to run the user's default mail client is included. There are multiple smaller features included, including a shortcut menu that appears when text is selected to paste the selected text directly into a search engine of choice. Finally, the browser includes a pop-up advertisement blocker which can be configured to allow pop-ups for individual sites, block only unrequested pop-ups, and open any pop-ups in new tabs in one window, thus preventing pop-unders. Criticism The Netscape Browser has been criticized for various reasons. Perhaps the most severe is the claim that, in contradiction to its claimed emphasis on security, its use of both the Trident and Gecko rendering engines means it unavoidably inherits all the vulnerabilities of both engines, making it potentially less secure than either Firefox or IE on their own. Renderer modality problems The switching between rendering engines may also confuse users, since the web browsing experience is very different depending on which is used. A standards based website will generally render better in Gecko thanks to its better standards support, but Netscape Browser renders whitelisted pages using Trident instead. "As the switching is transparent to the user, users are left wondering why their experience changes randomly across different websites". User interface issues The optional theme "Fusion" has also been criticized because it does not conform to the Microsoft human interface guidelines (HIG), either "Luna" or "classic" style, although the default theme, "Winscape", looks more like a traditional Windows application. There is also a claim that the usability of the browser is reduced by not obeying standard Windows manipulations. Similarly, the excessive nesting of tabs has been cited as a sign of generally poor interface design. The installation program of Netscape 8.12 prompts the user into which theme would be preferred, with the traditional "Winscape" being checked by default. Helper programs removed Some users have argued the formerly included email client and HTML editor were more valuable as part of the browser package than new features such as a live weather report and news ticker, especially since these applications were tradition in earlier versions. Firefox, upon which Netscape Browser is based, does not include an email client or HTML editor