Update ckeyoff.rst

A better explanation of potential bugs.
On behalf of Per Witte.

sphinx/source/C/ckeyoff.rst

@@ -22,33 +22,38 @@ There were problems with this command prior to v1.56.
 
 **Note 2**
 
-At some point CKEYOFFstarted to have to take a channel number, ie
-CKEYOFF #channel.
+At some point CKEYOFF required a channel number parameter, ie CKEYOFF
+#channel. If you don't specify a channel number the command falls back on the current
+S*BASIC's channel #0. 
 
-If you dont give a
-channel number the commands try to open their own channel - that hybrid
-number 0/1, as do a number of IO commands (at least in SMSQ/E). All well
-and good. But if you, say, open your first channel as number 3, as happens
-automatically if your first channel in a daughter SBASIC or Qlib compiled
-job, and you open it with ch = FOPEN("con_") then, if that channel is
-OUTLiNed to be smaller than the default channel, the call fails and returns
-to the routine - which gives up. But doesnt say anything! However, now
-there is dangling, open channel in the main channel table that SBASIC
-doesnt know about. So next time you use this command yet another channel is
-opened in the main channel table! And so it goes on ad finitum until the
-job is killed - or the system chokes.
+Unfortunately, if there isn't already a channel #0 open, for example, a program might have opened
+its first channel using:
 
-This is a rare circumstance, admittedly, but it is still a bug.
+1500 main = FOPEN("con_")
 
+In this case, the the CKEYOFF command will open a new console 
+channel and then try to set the window size of that 
+channel to the default size of 256x62. If, however, the program had already OUTLN'ed
+#main to a smaller size, in any dimension, than 256x62, then this call will fail.
 
-The bug fix is that
-if the circumstances described pertain, the call will return with an Out of
-Range error.
+And here's the bug: Instead of closing the failed console channel, the command
+simply returns without error. This leaves a "dangling" console channel open
+without an S*BASIC handle. And each repeated call to CKEYOFF/CKEYON opens
+another such channel!
+
+As of ptr_gen 2.07 and SMSQ/E 3.39, this bug should be fixed, in that an "Out of
+Range" error will be returned should the situation described above arise.
+
+The workaround for earlier versions is: Always use this command with a
+channel number *unless* there is definitely an available console channel #0!
+
+
+The bug fix is that, if the circumstances described pertain, the call will return with an "Out of
+Range" error.
 
 
 
 **CROSS-REFERENCE**
 
-:ref:`ckeyon` tells the Pointer Interface to
-recognise the cursor keys again.
+:ref:`ckeyon` tells the Pointer Interface to recognise the cursor keys again.