diff --git a/ChangeLog b/ChangeLog
index 5ddbfd576..7e5a34c6c 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,16 @@
+2008-06-02  Wolfgang Sourdeau  <wsourdeau@inverse.ca>
+
+	* UI/MailPartViewers/UIxMailPartICalViewer.m
+	([UIxMailPartICalViewer -canOriginalEventBeUpdated]): new template
+	accessor that return whether the use status has changed in the
+	original reply and if its sequence number concurs.
+
+	* UI/MailPartViewers/UIxMailPartICalActions.m
+	([UIxMailPartICalActions -updateUserStatusAction]): we accept the
+	modification if the sequence number from the reply is equal or
+	SUPERIOR (for Lightning bugs), rather than inferior, where the
+	reply is obsolete anyway.
+
 2008-05-31  Wolfgang Sourdeau  <wsourdeau@inverse.ca>
 
 	* SoObjects/Mailer/SOGoMailFolder.m ([SOGoMailFolder
diff --git a/UI/MailPartViewers/UIxMailPartICalActions.m b/UI/MailPartViewers/UIxMailPartICalActions.m
index 6d91a5fcd..77cd6e767 100644
--- a/UI/MailPartViewers/UIxMailPartICalActions.m
+++ b/UI/MailPartViewers/UIxMailPartICalActions.m
@@ -319,7 +319,7 @@
       eventObject = [self _eventObjectWithUID: [emailEvent uid]];
       calendarEvent = [eventObject component: NO secure: NO];
       if (([[emailEvent sequence] compare: [calendarEvent sequence]]
-	  != NSOrderedDescending)
+	  != NSOrderedAscending)
 	  && ([self _updateParticipantStatusInEvent: calendarEvent
 		    fromEvent: emailEvent
 		    inObject: eventObject]))
diff --git a/UI/MailPartViewers/UIxMailPartICalViewer.m b/UI/MailPartViewers/UIxMailPartICalViewer.m
index 66df01d20..52481cc66 100644
--- a/UI/MailPartViewers/UIxMailPartICalViewer.m
+++ b/UI/MailPartViewers/UIxMailPartICalViewer.m
@@ -416,4 +416,11 @@
 	  != NSOrderedSame);
 }
 
+- (BOOL) canOriginalEventBeUpdated
+{
+  return ([self hasSenderStatusChanged]
+	  && ([[inEvent sequence] compare: [storedEvent sequence]]
+	      != NSOrderedAscending));
+}
+
 @end /* UIxMailPartICalViewer */
diff --git a/UI/Templates/MailPartViewers/UIxMailPartICalViewer.wox b/UI/Templates/MailPartViewers/UIxMailPartICalViewer.wox
index d4f58af6e..91ba11468 100644
--- a/UI/Templates/MailPartViewers/UIxMailPartICalViewer.wox
+++ b/UI/Templates/MailPartViewers/UIxMailPartICalViewer.wox
@@ -84,7 +84,7 @@
 	</var:if>
 
 	<var:if condition="isReplySenderAnAttendee">
-	  <var:if condition="hasSenderStatusChanged"
+	  <var:if condition="canOriginalEventBeUpdated"
 	    ><p class="uix_ical_toolbar">
 	      <input id="iCalendarUpdateUserStatus" class="button"
 		type="button" label:value="Update status"/>