From the release notes:

This is mostly a bug fixed, performance improved, WinVNC version 3.3.6.
There are no major feature changes, and only one minor feature change.  As a
concession to useability, code for keeping the local client viewer open and
automatically resized upon changing the remote server screen resolution was
migrated from eSVNC/UltraVNC into this code.  Otherwise, the entire feature
set of WinVNC version 3.3.6 has remained unchanged.  I would have liked to
include TightVNC's local cursor handling, but that would have broken the VNC
viewers on other platforms.

Windows only, open-source. You can get it here:

binaries: http://www.coyoterd.com/WinVNC-336-patched-exe.zip
source: http://www.coyoterd.com/WinVNC-336-patched-src.zip