The places bar allows users to navigate via the common dialog directly to the
following locations: History folder, Desktop, My Documents, My Computer, and My
Network Places. When this registry value is enabled, Windows 2000 removes the
back button from the common dialog, preventing the user from browsing to the
previous folder accessed from the dialog.
Hive: HKEY_CURRENT_USER
Key: Software\Microsoft\Windows\CurrentVersion\Policies\Comdlg32
Name: NoBackButton
Type: REG_DWORD
Value: 1 enable
Applications that use the Windows
common dialog API will comply with this policy.