How to reorder an icon's sub-windows in taskbar [duplicate]

You can do this with 7 Taskbar Tweaker.

Just check the box Drag to reorder under Thumbnails section:

As stated on the app, it's allowing you to reorder from the thumbnail: hover the app on the taskbar and wait until the windows' thumbnail is shown, then click-and-drag the thumbnail to reorder it. The corresponding window on the taskbar will follow the order of the thumbnail.

The previously mentioned Taskbar Shuffle doesn't support Windows 7 yet, to my knowledge.

This is possible, but quite hacky.

Lets consider, you have three windows of the same application: A, B and C. You want them to be shown on task bar as [A][B][C], while they are shown in some other order. To achieve this do the following:

1. Activate the windows one by one in the order, which is reversal of the desired order, i.e. activate window C, then B, then A
2. Now window A is on top, window B is under A and window C is under B
3. Press Ctrl+Shift+Esc to open Windows Task Manager
4. Find explorer.exe process in Processes tab, select it and press End Process
5. Choose File->New Task (Run...), enter explorer and click OK.
6. When started, explorer arranges taskbar buttons according to the z-order of windows, so buttons will be arranged as [A][B][C]

This method will probably kill all Windows Explorer windows. If you need to preserve them, do the following:

1. Press Win+E to open Windows Explorer
2. Go to Organize->Folder and search options->View->Advanced settings:
3. Check Launch folder windows in separate process checkbox and click OK

Now, if you have at least one Windows Explorer window, then at step 4 of the original instruction you will see two explorer.exe processes: one responsible for taskbar and another responsible for Windows Explorer windows.

To distinguish which one is which, turn on Command Line column in Task Manager (View->Select Columns...>Command Line). The explorer.exe process responsible for taskbar (i.e. the one you need to kill) will not have any arguments in command line, so its command line will look like C:\Windows\explorer.exe. The other explorer.exe process will have much longer command line looking like this: C:\Windows\explorer.exe /factory,{ceff45ee....

No. Unfortunately, it is not possible yet. Opened instances of the same application are combined and their live thumbnails cannot be reordered.

Note that even if you disable Combine (Right-Click Taskbar -> Properties -> Taskbar panel -> Taskbar Buttons dropdown), an application with several instances opened will still move as one group.