[Octave-bug-tracker] [bug #50692] Command Window outputs spurious newline every 30 sec.

[John W. Eaton]

Follow-up Comment #38, bug #50692 (project octave):

When Octave starts on Windows, it runs in a Windows Console
(https://learn.microsoft.com/en-us/windows/console/consoles) and the state of
the underlying screen buffer
(https://learn.microsoft.com/en-us/windows/console/console-screen-buffers) is
displayed in a Qt QWidget object in the Octave GUI.

As far as I know, all the code for this functionality is in the
libgui/qterminal/libqterminal/win32 directory of the Octave sources.

A timer is created that causes the function  QConsolePrivate::monitorConsole
in Octave's QWinTerminalImpl.cpp file to be called every 10 milliseconds.

That function will reposition the cursor if the cursor position of the screen
buffer changes or insert output if the contents of the buffer have changed.

It is possible that something in Octave is causing that to happen.  If so,
something would have to be writing a newline character (or something similar)
to Octave's standard output stream.  But since this doesn't happen for
everyone, I don't think it is something that Octave is doing by default.  And
if it is something added locally or due to an add-on package, I would expect
behavior to be fixed if you delete all locally installed packages and/or start
Octave with the --norc option to prevent Octave from loading any
initialization files.

It is also possible that some external process is writing to console screen
buffer.

It seems that we need someone who observes this issue and who also has the
necessary expertise to debug it.  I don't have a Windows system, and even when
I had access to one for running Octave, I never observed the issue.

Even if I were able to observe the issue, I don't know exactly how I would
determine what process is writing to Octave's console screen buffer other than
disabling background processes that could be doing that until I found that the
behavior stopped.


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