BLIDBGHAN()                   Get / Set Blinker debug handle
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 Function : Get / Set the Blinker debug handle

 Syntax   : nuValue = BLIDBGHAN([nuhandle])

 Return   : Previous debug Handle

 This function is used to get or set the Blinker overlay manager debug
 handle. It returns the previous debug handle, and takes as an optional
 parameter the new handle it should be set to.

 The handle defaults to 1 for the screen unless it is overridden at link time
 using the BLINKER DEBUG HANDLE command or at run time using the /DHn setting
 in the BLINKER environment variable.

 The new handle is not validated and may be either 1 to send output to the
 screen, 2 to send output to the standard error device, 4 to send output to
 the printer, or the DOS handle of a file opened by the program with a DOS
 open file call.

 This handle is used as the default output handle for a number of the other
 Blinker debugging functions, so may be set once at the start of the program
 rather than passing it as a parameter to each function individually.

 Example:

    * Get the current debug handle
    *
    ? "The debug handle is currently", BLIDBGHAN()
    * Set the current debug handle to the printer
    BLIDBGHAN(4)