In Windows XP and Windows Vista, the program’s window buttons on Windows Taskbar will combine and group together when the number of windows or buttons increase and its length exceed the screen width. When the buttons for all opened windows of a program is combined or grouped together, only one button and label appears on the Taskbar, leaving the room to display on Taskbar for other software applications and icons of system tray (aka notification area).

For user who wants to let Windows group or combine together similar windows at a faster pace, such as after 3 or 4 similar windows from same application are opened so that Windows does not ‘squeeze’ on the size of the Taskbar’s button, Windows provides TaskbarGroupSize registry key which user can hack in order to change the behavior of how Windows group and combine similar Windows. It’s also possible to force all similar windows to always combine to just one button in Taskbar as similar to Windows 7 when two or more windows are opened.

TaskbarGroupSize is a setting-based registry value that defines the number of open windows of same application that appears on Taskbar before they are grouped together on the Taskbar into one button.

To modify Taskbar Group Size value, follow these steps:

  1. Run Registry Editor (RegEdit).
  2. Navigate to one of following registry key:

    For current logged on user: HKEY_CURRENT_USER\SOFTWARE\Microsoft\Windows\CurrentVersion\Explorer\Advanced

    For all user accounts on the computer: HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Explorer\Advanced

  3. In the right pane, create a new DWORD Value, and named the registry value entry as TaskbarGroupSize.
  4. Double click on the TaskbarGroupSize, and change its value to number of windows to open in Taskbar you desired. For example, a value of 3 will group together all windows into one button of an application when there is 3 or more windows opened.

    Combine Taskbar Buttons

    Tip: To force enable just one Taskbar button for all opened windows of a program in a style similar to Windows 7 “Always combine”, set TaskbarGroupSize value data to 2.

  5. Restart the computer or log out and log in again for the change to take effect.