Desktop Gadgets (available in Windows Vista and 7 only) are small add-ons that can display myriad of things - current weather and forecasts, news, CPU and disk usage, network traffic; perform searches via Bing or Google, show your upcoming appointments, etc. In Windows Vista, all Gadgets run in a special program named Windows Sidebar.
Windows 8 ships without any support for Gadgets - due to numerous security concerns, Microsoft has replaced them with Modern UI/Metro apps instead.
You can drag Gadgets to any place on screen you like and while any other window can overlap Gadgets, you can still bring all Gadgets temporarily to front and cycle through these by using keyboard shortcut Windows Key+G. In Windows Vista, you can activate Windows Sidebar by pressing Windows Key+Spacebar on keyboard.
Just like with toolbars in Internet Explorer, there is no point in adding too many Gadgets to Desktop. Every Gadget uses CPU and memory resources, so having many of them running might reduce performance.
You can change Windows Sidebar settings by opening Start menu (press Windows Key on your keyboard once) and typing "sidebar" into Search box.
Click Windows Sidebar Properties.
If you want to see Sidebar with Gadgets every time you start Windows Vista, leave the Start Sidebar when Windows starts box checked. If not, clear it.
There are rare cases when Sidebar should be always visible and overlap open windows, so leave the Sidebar is always on top of other windows unchecked.
You can select the side of screen Gadgets are displayed on by selecting Right or Left option.
In case you have multiple monitors connected, you can select the monitor for displaying Sidebar on. Select the monitor number from the Display Sidebar on monitor list.
Click OK after making changes.
By default, there are three Gadgets running in Windows Vista - Pictures slideshow, News and Clock. In Windows 7, there are no default Gadgets.
You can add any installed Gadget via Gadget Gallery.
In Windows Vista, right-click on an empty Sidebar area (or Windows Sidebar icon in Taskbar Notification area) and click the Add Gadgets... command, or click the plus sign on the top of Windows Sidebar.
In Windows 7, right-click on an empty Desktop area and click Gadgets.
Here are Windows default Gadgets. Not too many of them, but as described later, you can add Gadgets from Internet. Double-click on the one you want to add to your Sidebar or Desktop.
Let's use the Weather Gadget here as an example.
In Windows Vista, the Gadget defaults its location to Redmond (that's where Microsoft is); Windows 7 version of the Gadget looks up your regional settings and checks for weather in your country's capital city. If you have a GPS or other location-aware sensor in your computer or connected to your computer, the Gadget displays weather for your exact location. Nice!
You can add Desktop Gadgets from many sources. Most common is AddGadgets.com. Microsoft has closed its Gadgets section in Personalization Gallery and suggests using Windows 8's Modern UI/Metro-style apps instead.
Please be careful while adding Gadgets from the Internet - not all of these work perfectly and some might be malicious. It is strongly recommended to install Gadgets only from trusted and well-known sources. Using a free anti-virus program and WOT Safe Surfing Tool might be very helpful here.
If you are downloading an unverified Gadget submission, you will probably see another security warning by Windows Sidebar (Windows Vista) or Desktop Gadgets (Windows 7). This will tell that the gadget you downloaded has no digital signature (digital signatures are expensive and not all developers can afford them).
In case you run into trouble (computer performance problems, lockups, error messages) after adding an unverified Gadget, try turning that gadget off and see if that helps.
Continue by clicking Install.
After a few seconds you will see the new Gadget. As usual, you can drag it around, change its options or close it. The gadget will now also be available in Windows 7 Gadgets list (right-click on an empty Desktop area and click Gadgets), so that you can add it again later if you need to.
If you want to change any available options for a Gadget, such as location, move your mouse pointer on the Gadget and change your current location by clicking the wrench-shaped Options button.
Under options you can type in your current location, such as "Tartu, Estonia" or "Wyoming". Please note that the Find location automatically option in Windows 7 is disabled until you have a location-aware sensor (such as GPS) installed and connected.
You can also select to display temperature in Fahrenheit or Celsius. Click OK to accept changes and close options.
By default, all Gadgets will be added to Windows Sidebar or the right side of Desktop. To move a Gadget to a place you like, move your mouse pointer on the Gadget, click and hold on Drag gadget button and relocate the Gadget.
In Windows Vista, most Gadgets change to a larger size and some display more details after detaching from Sidebar. You can drag the Gadget back onto Sidebar and it will re-attach automatically and change back to smaller size.
Some Gadgets in Windows 7 have two different size options - smaller size and larger size. All Gadgets are smaller in size by default, and larger size typically displays more detailed information.
To see Weather Gadget in larger size, move your mouse pointer over the Gadget and click the Larger size button.
In Windows Vista, Gadgets change to a larger size and display more details only after detaching (dragging away) from Sidebar.
Now you can see forecast plus high and low temperatures. Notice that the previous Larger size button in Windows 7 changed its shape and is now called Smaller size. You can restore Gadget's original size by clicking on it.
In Windows Vista, drag the Gadget back onto Sidebar and it will re-attach automatically and change back to smaller size, or right-click the Gadget and select Attach to Sidebar.
As Gadgets are usually small in size, you might prefer to keep some of them on top of all other windows - or always visible. In Windows Vista, you can do this only for those Gadgets that are detached from Sidebar (larger in size). The second option is to keep Windows Sidebar itself always on top, as described in the beginning of this article.
To put a Gadget on top, right-click on the Gadget itself (not its toolbar!) and click Always on top.
If you want to disable the feature, right-click on the Gadget again and click Always on top again.
Keeping a Gadget always visible is a nice feature, but sometimes that Gadget hides the information you need to see - some text, for example. Luckily, there is an option to adjust a Gadget's opacity - how transparent it is.
To adjust opacity, right-click on the Gadget itself (not its toolbar!), select Opacity and click the percentage you need.
At 100%, there's no way to see what's behind the Gadget. At 20%, you can barely see the Gadget unless you move your mouse over it. Yup, moving the mouse pointer over a transparent Gadget sort of lights it up and turns on 100% opacity until you move your mouse pointer away from it.
Here's the weather Gadget at 20% opacity. Note how you can still see what's behind the Gadget.
If you do not want some Gadget on Sidebar or Desktop, move your mouse pointer on it and click the X shaped Close button. Most Gadgets forget their settings after this, so please be careful!
There may be reasons for disabling Sidebar or all Gadgets (performance, troubleshooting, etc) temporarily.
In Windows Vista, right-click on an empty Sidebar area and click Close Sidebar to leave Windows Sidebar program running, but hide all Gadgets. Alternatively, you can right-click the Windows Sidebar icon in Taskbar Notification area and click Exit - this will close the program until the next computer restart or until you start it manually again.
In Windows 7, right-click on an empty Desktop area, select View and click Show desktop gadgets.
In Windows Vista, some information on displaying Sidebar and its Gadgets again is displayed for a while after clicking Close Sidebar.
If you need to display Desktop Gadgets again in Windows Vista, you can right-click the Windows Sidebar icon in Taskbar Notification Area and select Open. In case you closed the whole program, open Start menu, type "sidebar" into Search box and click Windows Sidebar in the results.
In Windows 7, just right-click on an empty Desktop area, select View and click Show desktop gadgets again.