I told him that behavior is changeable and I post the steps in this post.
Its simple as 123 :
1. Right click on free area ( I’ve highlight in red color).
Make sure not right click on icon.
2. Windows 7 Taskbar and Start Menu Properties
Change Taskbar appearance, three options available :
- Lock the taskbar
- Auto hide the taskbar
- Use small icons
Check “Use small icons” as shown in the picture and click Apply button.
3. See the difference
Smaller icon now in charge, of course you can switch it to big icons with the same method.