Asynchronous agent requests on Windows. Actually, I've kept the

ability to do synchronous ones as well, because PSCP and PSFTP don't
really need async ones and it would have been a serious pain to
implement them. Also, Pageant itself when run as a client of its
primary instance doesn't benefit noticeably from async agent
requests.

[originally from svn r3154]

putty.h

@@ -492,6 +492,10 @@ struct config_tag {
  * These flags describe the type of _application_ - they wouldn't
  * vary between individual sessions - and so it's OK to have this
  * variable be GLOBAL.
+ * 
+ * Note that additional flags may be defined in platform-specific
+ * headers. It's probably best if those ones start from 0x1000, to
+ * avoid collision.
  */
 #define FLAG_VERBOSE     0x0001
 #define FLAG_STDERR      0x0002