I have never noticed this before because I have the Control Panel displayed as a menu on the Start Menu. I recommend trying it this way yourself if you haven't already. I find it to be far more convenient to have the Control Panel displayed as a menu. This is due to being able to do it back in Windows 95/98/XP using TweakUI.
Anyway, it seems to me like there's no way to change the behavior because Administrative Tools is just a special folder full of shortcut files that point to the different programs collectively known as Administrative Tools. The Control Panel in Windows 7 cannot display folders due to the way it has been designed.
It's also not the only thing that requires a new Window. The following Control Panel items also need a new Window:
- Color Management
- Date and Time
- Desktop Gadgets
- Device Manager
- Flash Player (if it's installed)
- Folder Options
- Getting Started
- Indexing Options
- Intel Rapid Storage Technology (if it's installed)
- Internet Options
- Java (if it's installed)
- Keyboard
- Mail
- Mouse
- NVIDIA Control Panel (if it's installed)
- Quicktime (if it's installed)
- Region and Language
- Sound
- Taskbar and Start Menu
- Windows Anytime Upgrade
- Windows CardSpace
- Windows Defender
So there are just some things in the Control Panel that cannot be displayed inside of the Control Panel window because of the way the Control Panel coded. As you can see, the things that
do open in the Control Panel window slide in. So, they're already a part of that Window - or something like that. I don't know how to explain it.
Either way, there's no way to change it without having Microsoft release a patch or a Service Pack to change it so that all of the Control Panel items slide in just like all of the items I didn't list here. However, that would be a
huge change to Windows 7 and its code. It would make for an enormous service pack, probably the biggest one ever released.