fix for #7891. commit db after we mark a header read.

mailnews/db/msgdb/src/nsNewsDatabase.cpp

@@ -138,6 +138,17 @@ NS_IMETHODIMP nsNewsDatabase::MarkHdrRead(nsIMsgDBHdr *msgHdr, PRBool bRead,
 	// give parent class chance to update data structures
 	rv = nsMsgDatabase::MarkHdrRead(msgHdr, bRead, instigator);
 
+	// sspitzer:
+        // yes, it is expensive to commit every time here.
+	//
+	// if we crash (the horror!) before we commit, the user will
+	// lose all there mark as read changes.
+	// 
+	// since committing every time is expensive if we mark a
+	// whole bunch of headers as read, we should commit after we are
+	// done marking.
+        Commit(kSessionCommit);
+	
 	return rv;
 }