Speed Up Windows 7 Taskbar Navigation with a Registry HackLaunch regedit.exe (Win+R, then paste regedit.exe)
Navigate in the left tree control to HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Explorer\Advanced
Go to Edit->New->DWORD (32-bit) Value
Name the value LastActiveClick
Hit enter to assign the value and change it to 1
Restart Explorer and you're good to go.
To restart Explorer without rebooting, open the Task Manager (Ctrl+Shift+Esc) and end the Explorer.exe process. Then create a new task (under "File") and paste "explorer.exe".
(From a post in
lifehacker)