Index: src/ch/task.h
===================================================================
diff -u -N -r22573f5fa8bfbf68a19deb7631962e026f028045 -r4a3c74a38b00e7793d1e61107a824060e6c2ea95
--- src/ch/task.h	(.../task.h)	(revision 22573f5fa8bfbf68a19deb7631962e026f028045)
+++ src/ch/task.h	(.../task.h)	(revision 4a3c74a38b00e7793d1e61107a824060e6c2ea95)
@@ -69,6 +69,9 @@
 #define E_CANCEL			0x02
 #define E_PAUSE				0x03
 
+// special value representing no task
+#define NO_TASK_SESSION_UNIQUE_ID				0
+
 // structure for getting status of a task
 struct TASK_DISPLAY_DATA
 {