An irritating behavior for someone who is running Windows 7, Windows 8, or Windows 10 is that when you click on an application where you have multiple windows open, it will give a preview as a thumbnail for each open window. Then you have to click a second time on the thumbnail for it to switch to the window you want to use. According to www.howtogeek.com, you can perform a simple hack that will toggle through the last active window:

1. Hit the Windows key.
2. Type regedit and hit enter.
3. Navigate to the following directory by clicking the arrows next to each folder:

   HKEY_CURRENT_USERSoftwareMicrosoftWindowsCurrentVersionExplorerAdvanced

4. In this directory, right-click on the right side and select New → DWORD (32-bit) Value.
5. Name this LastActiveClick.
6. Set the value to 1 by double clicking it and changing the value under Value Data to 1.
7. Either log off or restart the explorer.exe process through the task manager.