Moved scrollbar tracking code to scroll.c.
Avoid unnecessary coordinates conversion in NC_HandleSysCommand.

include/nonclient.h

diff --git a/include/nonclient.h b/include/nonclient.h
index 0b95d2a..2d928a4 100644
--- a/include/nonclient.h
+++ b/include/nonclient.h
@@ -15,7 +15,7 @@
 extern LONG NC_HandleNCHitTest( HWND hwnd, POINT pt );
 extern LONG NC_HandleNCLButtonDown( HWND hwnd, WPARAM wParam, LPARAM lParam );
 extern LONG NC_HandleNCLButtonDblClk( HWND hwnd, WPARAM wParam, LPARAM lParam);
-extern LONG NC_HandleSysCommand( HWND hwnd, WPARAM wParam, POINT pt );
+extern LONG NC_HandleSysCommand( HWND hwnd, WPARAM wParam, LPARAM lParam );
 extern LONG NC_HandleSetCursor( HWND hwnd, WPARAM wParam, LPARAM lParam );
 extern void NC_DrawSysButton( HWND hwnd, HDC hdc, BOOL down );
 extern BOOL NC_DrawSysButton95( HWND hwnd, HDC hdc, BOOL down );