Disables the ability to change the specified default handler (PDF viewer).
The UI configuration does not set any key in HKCU. Instead, changing a setting invokes the installer which sets the key in HKLM. The default and application behavior varies depending on what is installed. A value of 1 disables the user's ability to change the default handler. Possible values include:
0 (or null): Allow the user to change the default viewer.
1: Don't allow the user to change the default viewer.
GUI mapping - Edit > Preferences > General > Select Default PDF Handler
| Registry Hive | HKEY_LOCAL_MACHINE |
| Registry Path | SOFTWARE\Policies\Adobe\Acrobat Reader\11.0\FeatureLockdown |
| Value Name | bDisablePDFHandlerSwitching |
| Value Type | REG_DWORD |
| Enabled Value | 1 |
| Disabled Value | 0 |