WM_CHAR of Ctrl-C, Ctrl-V appear to have no effect in WinXP-SP2 riched20 control

I am trying to fix a few tests for riched20 that attempt to recover the
text from the control with WM_GETTEXT and assume the text will be
recovered unchanged. As demostrated in a patch I sent a few minutes ago,
this assumption is not true when the text to recover contains unbalanced
\r, which are converted to \r\n. However I have a strange problem. On my
setup (WinXP-SP2 with cygwin), sending Ctrl-C and Ctrl-V with WM_CHAR
appears to have no effect on the riched20 control used for the tests.
Therefore the text buffer is not modified and the end text remains
unchanged. I want to check whether this tests fails in the same way for
anybody else, and if not, to receive suggestions on what might be wrong
with my setup.