Windows Desktop Gadgets

The Windows Desktop Gadgets (called Windows Sidebar in Windows Vista) was a widget engine for Microsoft Gadgets, with program name sidebar.exe. It was introduced with Windows Vista, in which it features a sidebar anchored to the side of the desktop. Its widgets, called Gadgets, can perform various tasks, such as displaying the time and date and showing the CPU usage.

Microsoft retired Windows Live Gallery in late 2011 when developing Windows 8. In subsequent months when vulnerabilities were publicized concerning exploitative Gadgets, Microsoft recommends to current users to disable the Sidebar and discontinue using Gadgets. The Windows 8 Live Tiles run in a more restrictive security environment, making them less risky, but also less useful for some purposes, like system monitoring.

Overview
Windows Desktop Gadgets contains mini-applications or Gadgets which are based on a combination  of Script and HTML. They may be used to display information such as the system time and Internet-powered features such as RSS feeds, and to control external applications such as Windows Media Player. Gadgets can run "docked" in the sidebar or they can "float" anywhere on the desktop. It is also possible to run multiple instances of a gadget simultaneously.

Windows Vista ships with eleven gadgets: Calendar, Clock, Contacts, CPU Meter, Currency Conversion, Feed Headlines, Notes, Picture Puzzle, Slide Show, Stocks, and Weather. Several other gadgets available during the Vista beta such as App Launcher, Feed Viewer, Number Puzzle, Recycle Bin and Egg Timer were removed. Windows 7 adds a Media Center gadget and removes the Contacts, Notes and Stocks gadgets. Desktop Gadgets were included in Windows 8 up to the Release Preview but removed from the RTM version. Windows Sidebar is not available on Microsoft Windows Server 2008, 2008 R2, 2012, or 2016.

Originally, Microsoft provided a link to a web site called Windows Live Gallery where additional Sidebar gadgets that have been created by third party clients could be downloaded. The site was officially retired on October 1, 2011. Citing security, Microsoft has released a Fixit tool to disable Desktop Gadgets on all operating systems. There are also tools from third party websites that can install Desktop Gadgets on Windows 8 and Windows 10.

History
Sidebar originated in a Microsoft Research project called Sideshow (not to be confused with Windows SideShow.) It was developed in the summer of 2000, and was used internally at Microsoft. It had many similarities to current desktop gadget software, including a clock, traffic reports, and IM integration.

The Sidebar appeared in build 3683 of Windows Vista circa September 2002, at the time codenamed "Longhorn", and was originally intended to replace the notification area or Quick Launch toolbar in Windows, but these plans were scrapped after the development reset in mid-2004.

The Windows Sidebar was rebuilt for and began to appear in Windows Vista builds in the second half of 2005. Some reviewers and Macintosh enthusiasts have pointed out the Sidebar's similarities in form and function to Konfabulator (now Yahoo! Widget Engine), which appeared several years previously, and the Dashboard widget engine first included with Apple Inc.'s Mac OS X v10.4, which had been released a few months earlier.

In Windows 7, Windows Sidebar was renamed Windows Desktop Gadgets, and the sidebar itself is not included in Windows 7. It can be reinstated on Windows 7 if the program files are copied over from Windows Vista.

As of Q4 of 2011, Microsoft retired Windows Live Gallery, stating on their gadgets page that "In order to focus support on the much richer set of opportunities available for the newest version of Windows, Microsoft is no longer supporting development or uploading of new Gadgets." The page also has links to help users disable the Sidebar and Gadget functionalities of Windows out of concern for vulnerabilities.

Although removed from Windows 8 and 10, the Desktop Gadgets can be added back to the Windows 8 desktop using the unofficial 8Gadgetpack, or "Gadgets Revived". Other suggested replacements for system monitoring include 3rd party full desktop overlays, such as Rainmeter, which have their own customization system.