[tex-k] Question about MetaFont online display

[Igor Liferenko]

Hi all,

I would like to report a possible bug in MetaFont.

I have setup a test environment to reproduce it:

    git clone git://github.com/igor-liferenko/mf && cd mf
    make x
    ./mf test

In the output you will see redundant calls to blankrectangle and updatescreen:


This is METAFONT, Version 2.7182818 (TeX Live 2017) (preloaded base=mf)
(test.mf
initscreen called

blankrectangle called

updatescreen called

blankrectangle called

updatescreen called
)
*


Except these duplicate calls being useless, they may also cause undesirable
small initial blinking effect in an online display driver.

Anyway, these duplicate calls are strange and cause a question for
what they are needed.

Does anybody have an opinion on this?

Regards,
Igor