Windows 7's taskbar is undoubtedly a great addition to Windows, but if you've got more than one application window open, you've got to either click twice or patiently hover to navigate to an open window. Reader Richard details how he fixed this:
I've been frustrated as of late with the Windows 7 taskbar. The fundamental problem was that you needed two clicks to navigate to your document if you have two instances of a program running. Or you're stuck with hovering for what feels like an eternity.
At Windows 7 Forums I finally found a nice step in the right direction. Full post is here, but summarised below. In short, this hack causes an applications last active window to activate when you click the taskbar icon, and the next window in the second click, etc. The hover preview still works if you hover to begin with, but if you want the preview after you've click on an app's icon in the taskbar, you can Ctrl+Click to bring it back. The current default settings are the exact opposite (that is, Ctrl+Click cycles through the last active windows of an application).
Launch regedit.exe (Win+R, then paste regedit.exe) Navigate in the left tree control to HKEY_CURRENT_USERSoftwareMicrosoftWindowsCurrentVersionExplorerAdvanced 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".