NT4 copies the Win95 feature of using animated rectangles to provide a "zooming" effect when windows are opened and closed. To control

Hive: HKEY_CURRENT_USER
Key: Control Panel\Desktop\WindowMetrics
Name: MinAnimate
Type: REG_DWORD
Value: 0 disable
Value: 1 enable

See q226931 - How to Minimize Graphics Use with Terminal Server if you want to minimize the effects for terminal server users.

Gives an in-depth look at the NT/Windows 95/98 system policies. Step-by-step walkthroughs.

title says it all