mouse scroll wheel broken on multiple monitors

When multiple monitors are setup in XP such that there is a monitor to the left of the primary monitor, mouse coordinates for these monitors have a negative X value. Unfortunately, the code in ClientConnection::WndProc does not handle signed numbers properly when extracting from the LPARAM, causing the "WindowFromPoint(coords)" call on line 2141 of ClientConnection.cpp to fail. This results in the mouse scroll wheel not working.

This patch properly extracts the signed coordinate values from LPARAM:

--- tightvnc-1.3.10\vncviewer\ClientConnection.cpp Sat Feb 07 23:29:42 2009
+++ tightvnc-1.3.10-mdr0\vncviewer\ClientConnection.cpp Tue Jun 02 13:44:22 2009
@@ -2132,8 +2132,8 @@
SetFocus(hwnd);

POINT coords;
- coords.x = LOWORD(lParam);
- coords.y = HIWORD(lParam);
+ coords.x = ((int)(short)LOWORD(lParam));
+ coords.y = ((int)(short)HIWORD(lParam));

if (iMsg == WM_MOUSEWHEEL) {
// Convert coordinates to position in our client area,