The formatting rectangle is set with EM_SETRECT, and retrieved with
EM_GETRECT, so it corresponds to rcFormat in the code. This defines the
area that the richedit control should draw the text so that it is
offset by the top-left corner of the formatting rectangle, and clipped
so that it doesn't draw past the bottom or right hand side. Thus this
is important for implementing windowless richedit controls to not
interfere with the rest of the window.
There were several methods that do not have a HRESULT for a return
value, so returning E_NOTIMPL is not appropriate. For all the BOOL
return values FALSE was returned to indicate the operation was not
performed.
EditWordBreakProc documented the third parameter as being the number
of unicode characters in the string for richedit 2.0 and up. It turns
out that it should actually be the number of bytes in the string.
For some reason EM_POSFROMCHAR was returning 0 when the position was
equal to the end of the text, or beyond the end of the text. Instead
it should use the position at the end of the text for both these
cases. The x value was also seen to be offset by 1 according to the
tests.
Previously the shortcuts for cut, copy, paste, undo, redo, and select
all were being handled during the WM_CHAR message. These tests show
that these shortcuts should be handled with the WM_KEYDOWN message
instead.
There were some notifications that weren't sent in ME_UpdateRepaint
while redraw was disabled, so this verifies that they are not sent
with redraw disabled.
The test for EM_GETLINE was testing to make sure the null terminating
character was written at the end of the text as long as the buffer was
long enough, and also tested to make sure that no other bytes were
written after this null terminating character. This is consistent with
Windows 2000 and up, but not for previous versions of Windows.
The values returned by EM_SETPARAFORMAT and EM_GETPARAFORMAT previously
indicated an error, and the included tests shows that Windows behaves as
documented.
This is a minimal model of what happens in Corman Lisp 3.0 -
subclassed window class that unconditionally calls ShowScrollBar() to
force scrollbar visibility.