--- a/rep/gui/RPanel.java	Mon Nov 10 22:19:34 2008 +0900
+++ b/rep/gui/RPanel.java	Mon Nov 10 22:21:52 2008 +0900
@@ -106,9 +106,12 @@
 			
 		}else if(event.getSource() == selectButton){
 			//System.out.println("RPanel.actionPerformed() : editorSelectedRow = " + editor_table.getSelectedRow());
+			int selectedSession = session_table.getSelectedRow();
+			if (selectedSession<0) return;  // no sessin is selected
+			int selectedEditor = editor_table.getSelectedRow();
 			listener.buttonPressed(
-					new SelectButtonEvent(editorList.get(editor_table.getSelectedRow()),
-					sessionList.get(session_table.getSelectedRow())));
+					new SelectButtonEvent(editorList.get(selectedEditor),
+					sessionList.get(selectedSession)));
 		}else if(event.getSource() == closeButton){
 			listener.buttonPressed(new CloseButtonEvent(sessionList.get(session_table.getSelectedRow()), listener));
 		}