wd: cursor movement produces broken display content

[winspool]

I discovered the issue with $WATCOM/binl/wd, but to make it easier for non linux users,
I reproduced the issue with %WATCOM%\binnt\wd.exe from the current "ci" snapshot on win11:
(binnt64\wd.exe [and wdw.exe] fail to start: "TRAP Loader: Unable to load module file")

• Build a simple "hello world" style program
  (I use owcc hello.c -g -o hello_win32.exe) hello.c.txt

• Start %WATCOM%\binnt\wd.exe with the resulting hello_win32.exe

• Screenshot after wd.exe comes up:
  (* Unfortunately, the "Locals" window is active. An active "Source" window would be better)
  (* The orange square left of the "File" menu is the cursor from OS, but the cursor from wd.exe is different)

1. Activate the "Source" window
2. Press "Cursor right" the first time: Display content is still ok
3. Press "Cursor right" the second time: Display content is broken: "main(void)" disappeared
4. Press "Cursor down" two times: The "printf" line disapeared:
5. More cursor moves destroy more of the window content

• Activating the "Assembly" windows and moving the cursor around produces similar garbage:
  Example screenshot: