User`s guide

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Lock Window Services API—Function 61
This function allows the application to obtain or release exclusive control of the presentation space
window services.
Prerequisite Functions
Connect Window Services (function 101).
WinHLLAPI(LOCKWSAPI,lpbyString,lpwLength,lpwReturnnCode)
Parameter Description
Data String Locking parameters - a 3-byte string with the following
format:
Byte 1 Short name session ID, or space or null for the
current session.
Byte 2 One of the following:
u WHLL_LOCKAPI_LOCK to lock the API.
u WHLL_LOCKAPI_UNLOCK to unlock the
API.
Byte 3 One of the following:
u WHLL_LOCKAPI_RETURN to return if
the API is already locked.
u WHLL_LOCKAPI_QUEUE to queue the
lock request if the API is already locked.
Data Length Must be specified (normally 3).
PS Position NA.
Code Description
WHLLOK The function was successful.
WHLLNOTCONNECTED An invalid presentation space was specified, or was not
connected for window services.
WHLLPARAMETERERROR An invalid option was specified.
WHLLSYSERROR The function failed due to a system error.
WHLLNOTSUPPORTED The function was not supported by the emulation program.
WHLLPSENDED The session stopped.
WHLLLOCKERROR If _LOCK, the API was already locked.
If _UNLOCK, the API was not locked.
If the API is locked, Window Services functions are rejected until the API is unlocked by using the
UNLOCK option, or by disconnecting or resetting the presentation space.
Function Call
Call Parameters
Return Codes
Remarks