bug#4710: 23.1.50; Bad display of underlines crossing line boundaries

If you have an underline text property that crosses a line boundary it
will be displayed in a rather disturbingly way. The whole indentation on
the next line will be underlined.

For an example see https://bugs.launchpad.net/nxhtml/+bug/449837 where
there are some images.


If Emacs crashed, and you have the Emacs process in the gdb debugger,
please include the output from the following gdb commands:
    `bt full' and `xbacktrace'.
If you would like to further debug the crash, please read the file
c:/emacs/u/090928/emacs/etc/DEBUG for instructions.


In GNU Emacs 23.1.50.1 (i386-mingw-nt5.1.2600)
 of 2009-09-28
Windowing system distributor `Microsoft Corp.', version 5.1.2600
configured using `configure --with-gcc (3.4) --no-opt --cflags
-Ic:/g/include -fno-crossjumping'