Usually, while working you must have to run multiple windows simultaneously. But when you select a particular window, the other ones hide behind them. This event becomes irritating in many occasions.
As for example suppose you are surfing in a browser and at the same time you are watching a video in Windows Media Player. As soon as you click on the browser, the Windows Media Player disappears, and as you have no alternative you restore that player from task bar.
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Again in case for copy-paste the same thing happens, it prevents you to drag a file or folder from a window to another.
But there is a utility that lets you to place a particular window on top of the others. Here I have discussed about it.
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Always on Top is a free utility that helps you to stick any window in your desktop over the others. Download it and double click on the downloaded file. Now while working with multiple windows just select the window you want to keep on top, and press ctrl+space. Open any window,your desired window will be on top of the others.
If you want to disable that window from being in top and restore as default, just as before select it and press ctrl+space again.