The default behavior of the ADD Fonts wizard is to display all font files.

This behavior is controlled by the TTEnable Value Name, a string (REG_SZ) data type at
HKEY_CURRENT_USER\Software\Microsoft\Windows NT\CurrentVersion\TrueType. When the data value is 1, or when the TTEnable Value Name is not present, all font files are displayed. When TTEnable is NOT 1, the ADD Fonts wizard only displays fonts with file name extensions .FON and .FO_.

NOTE: The TTonly Value Name at this sub-key is obsolete and no longer used.

To set TTEnable to 0 using REG.EXE, built into Windows XP, Windows Server 2003, and Windows Vista, or installed from the Windows 2000 Support Tools:

1. Open a CMD.EXE windows.

2. Type the following command and press Enter:

REG ADD "HKCU\Software\Microsoft\Windows NT\CurrentVersion\TrueType" /V TTEnable /F /D 0