This is a minimal model of what happens in Corman Lisp 3.0 -
subclassed window class that unconditionally calls ShowScrollBar() to
force scrollbar visibility.

Alternate method of forcing (in)visibility of scrollbars, with SetWindowLongA().

Some applications have never heard of ES_DISABLENOSCROLL and attempt
to force scrollbars to be always shown (with ShowScrollBar() or
similar) when otherwise richedit would hide them. If richedit attempts
to wrestle control back, a recursive loop of requests can result if
app overrides WM_SIZE behavior. Apparently native never reads the
scrollbar state, and operates from some sort of internal state, so
that scrollbars can be modified externally without native trying to
wrestle back control. This is confirmed by attached tests. An
exception: EM_SCROLL will restore visibility to a scrollbar that was
forcibly hidden.

Implement Japanese auto detect, JIS and EUC encoding conversions to
Unicode and back. These conversions are not done in code pages but are
simple algorithms.

The minimal height should be saved so that it survives WM_SIZE or WM_SETFONT.