Man page 3 : XkbChangeMap

XkbChangeMap - Update only partial components of a keyboard description, modify the appropriate fields in the server and map components of a local copy of the keyboard description

Bool XkbChangeMap (Display * dpy , XkbDescPtr xkb , XkbMapChangesPtr changes );

• - dpy
      connection to X server
• - xkb
      description from which new values are taken
• - changes
      identifies component parts to update

To update only partial components of a keyboard description, modify the appropriate fields in the server and map components of a local copy of the keyboard description, then call XkbChangeMapwith an XkbMapChangesRec structure indicating which components have changed. XkbChangeMapcopies any components specified by the changesstructure from the keyboard description, xkb,to the X server specified by dpy. If any components specified by changesare not present in the xkbparameter, XkbChangeMapreturns False. Otherwise, it sends a request to the server and returns True. XkbChangeMapcan generate BadAlloc, BadLength, and BadValue protocol errors.

• True
                 The XkbChangeMap function returns True if the components specified by changesare present in the xkbparameter.
• False
                 The XkbChangeMap function returns False if the components specified by changesare not present in the xkbparameter.

Use the XkbMapChangesRec structure to identify and track partial modifications to the mapping components and to reduce the amount of traffic between the server and clients.

typedef struct _XkbMapChanges {
    unsigned short   changed;            /(** identifies valid components in
structure */
    KeyCode          min_key_code;       /(** lowest numbered keycode for device
*/
    KeyCode          max_key_code;       /(** highest numbered keycode for device
*/
    unsigned char    first_type;         /(** index of first key type modified */
    unsigned char    num_types;          /(** # types modified */
    KeyCode          first_key_sym;      /(** first key whose key_sym_map changed
*/
    unsigned char    num_key_syms;       /(** # key_sym_map entries changed */
    KeyCode          first_key_act;      /(** first key whose key_acts entry
changed */
    unsigned char    num_key_acts;       /(** # key_acts entries changed */
    KeyCode          first_key_behavior; /(** first key whose behaviors changed */
    unsigned char    num_key_behaviors;  /(** # behaviors entries changed */
    KeyCode          first_key_explicit; /(** first key whose explicit entry
changed */
    unsigned char    num_key_explicit;   /(** # explicit entries changed */
    KeyCode          first_modmap_key;   /(** first key whose modmap entry changed
*/
    unsigned char    num_modmap_keys;    /(** # modmap entries changed */
    KeyCode          first_vmodmap_key;  /(** first key whose vmodmap changed */
    unsigned char    num_vmodmap_keys;   /(** # vmodmap entries changed */
    unsigned char    pad1;               /(** reserved */
    unsigned short   vmods;              /(** mask indicating which vmods changed
*/
} XkbMapChangesRec,*XkbMapChangesPtr;

BadAlloc

               Unable to allocate storage

BadLength

               The length of a request is shorter or longer than that required to minimally contain the arguments

BadValue

               An argument is out of range