I have attached a screen shot of the issue.  The issue occurs when Emacs is in split window mode, X session and M-x shell is invoked.  The shell is ksh93.  I tried finding the Emacs bug tracker, however this is the only method I found to file a bug. This has been reproduced by others.

Screenshot of issue:

PS2 is printed multiple times during the resize.  When entered is pressed after the resize, multiple ^L s are displayed.  I set PS2="" and the brackets are omitted, however ^L still remain after pressing enter.

Is this a known issue?  I have CC'd KSH list in case the problem is on the ksh93 side.

Thanks

Emacs 26.1 build 2.

1 [debian:~]$ echo $0

-ksh93

2 [debian:~]$ ksh93 --version

  version         sh (AT&T Research) 93u+ 2012-08-01

3 [debian:~]$ echo ${.sh.version}

Version AJM 93u+ 2012-08-01