XkbQueryExtension to check for the presence and compatibility of the
extension in the server and to initialize the extension. Because of potential
version mismatches, you cannot use the generic extension mechanism functions
XInitExtension ) for checking for the presence of, and
initializing the Xkb extension.
You must call
XkbOpenDisplay before using any other Xkb
library interfaces, unless such usage is explicitly allowed in the interface
description in this document. The exceptions are:
XkbIgnoreExtension, XkbLibraryVersion, and a handful of audible-bell functions. You should not use
any other Xkb functions if the extension is not present or is uninitialized. In
general, calls to Xkb library functions made prior to initializing the Xkb
extension cause BadAccess protocol errors.
XkbQueryExtension both determines whether a compatible Xkb extension is present
in the X server and initializes the extension when it is present.
XkbQueryExtension function determines whether a compatible version of the X
Keyboard Extension is present in the server. If a compatible extension is
XkbQueryExtension returns True; otherwise, it returns False.
If a compatible version of Xkb is present,
XkbQueryExtension initializes the
extension. It backfills the major opcode for the keyboard extension in
opcode_rtrn, the base event code in
event_rtrn, the base error code in
error_rtrn, and the major and minor version numbers of the extension in
minor_in_out. The major opcode is reported in the
req_major fields of some Xkb events. For a discussion of the base event code.