Adding greatly to the severity of the problem is the patching mechanism used to add functions to the operating system, known as CDEVs and INITs or Control Panels and Extensions. Third party developers also make use of this mechanism to add features, including screensavers and a hierarchical Apple menu. Some of these third-party control panels became almost universal, like the popular After Dark screensaver package. Because there was no standard for use of these patches, it is not uncommon for several of these add-ons — including Apple's own additions to the OS — to use the same patches, and interfere with each other, leading to more crashing.