Thank you.

>I mean, the same way I minimize and restore/maximize a single window (by LeftClick), I'd like to have with group (Shift+LeftClick).
So, this desired behavior requires to create it manually?! Did I understand you correctly?

Adding also the others built in Windows features (Tiles) to taskbaritem, would be much welcomed.

Antoher problem:
When one window is Maximized, and the other windows are not. Do: Minimize manually only the others. Then do "Restore all group items".
Expected: All Minimized are restored, but the Maximized remains Maximized.
Problem: Sometimes, the Maximized window is restored too.

I've got this :(

I don't know what is better (Ctrl/Shift), but till now I used the Shift when I was dealing with a Group.
So for closing a group I used Shift+MiddleClick.
Now, with the new options, I'd probably want to use Shift+LeftClick for both Minimize/Restore a Group, I mean, the same way I minimize and restore/maximize a single window (by LeftClick), I'd like to have with group (Shift+LeftClick).
Do you think it can be done (to use the same hotkey)?
Maybe by:
When launching the hotkey, it will check the status of the clicked button: if it is minimized then run
Restore Group function. If it is Resotred/Maximized then run Minimize Group function.

If you want to set a fixed size:
http://www.sevenforums.com/tutorials/21233-taskbar-change-icon-button-width-size.html
It would be nice to have something like resize cursor appearing after few seconds, for temporary resizing.

Try copy-paste from the Taskbar Inspector.
Taskbar Inspector > Select > Ctrl+C
Paste it in Notepad.

I find "Close all group items" is very helpful.
It would be greatly appreciated if we can also "Close all group items" by using "Mouse click event" on Thumbnail Preview.