If you are a user of Windows XP and like your Taskbar organized, you will no doubt have the Grouping similar taskbar buttons” options enabled.
By default, when you enable the Group similar taskbar buttons option in Taskbar properties, items are grouped only when the taskbar buttons begin to get too small, and then the item that you opened first, is grouped first. This saves room on the taskbar by grouping similar entries (for example, all open Microsoft Word documents) together. However this does not always function as expected or wanted.
To change this behavior, create a “TaskbarGroupSize” DWORD entry in the following registry key:
The values for this key are:
0 – (Default) Group by age (oldest group first)
1 – Group by size (largest group first)
2 – Group any group of size 2 or more
3 – Group any group of size 3 or more
Log off and then back on for this change to take effect.