Man page 3 : XkbLatchModifiers

XkbLatchModifiers - Latches and unlatches any of the eight real keyboard modifiers

Bool XkbLatchModifiers (Display * display , unsigned int device_spec , unsigned int affect , unsigned int values );

• display
      connection to the X server
• device_spec
      device ID, or XkbUseCoreKbd
• affect
      mask of real modifiers whose lock state is to change
• values
      1 => lock, 0 => unlock; only for modifiers selected by affect

XkbLatchModifierssends a request to the server to latch the real modifiers selected by both affectand valuesand to unlatch the real modifiers selected by affect, but not selected by values. XkbLatchModifiersdoes not wait for a reply from the server. It returns True if the request was sent, and False otherwise. The functions in this section that change the use of modifiers use a mask in the parameter affect. It is a bitwise inclusive OR of the legal modifier masks:

• True
                 The XkbLatchModifiersfunction returns True if a request was sent to the server to latch the real modifiers selected by both affectand valuesand to unlatch the real modifiers selected by affect, but not selected by values.
• False
                 The XkbLatchModifiersfunction returns False if the request was not sent.