Bug 329415 Trying to remove exceptions in recurrencedialog with no exceptions selected throws JS-errors. patch by robin.edrenius@gmail.com, r=jminta

calendar/base/content/calendar-recurrence-dialog.js

@@ -57,6 +57,8 @@ function onLoad()
 
     opener.setCursor("auto");
 
+    checkSelectedException();
+
     self.focus();
 }
 
@@ -357,6 +359,7 @@ function removeSelectedException()
         window.removedExceptions.push(item.date);
     }
     exceptionList.removeItemAt(exceptionList.getIndexOfItem(item));
+    checkSelectedException();
 }
 
 function splitRecurrenceRules(recurrenceInfo)
@@ -375,3 +378,13 @@ function splitRecurrenceRules(recurrenceInfo)
 
     return [rules, exceptions];
 }
+function checkSelectedException()
+{
+    var exceptionList = document.getElementById("recurrence-exceptions-listbox");
+    var item = exceptionList.selectedItem;
+    if (!item) {
+        document.getElementById("remove-exceptions-button").setAttribute("disabled", "true");
+    } else {
+        document.getElementById("remove-exceptions-button").removeAttribute("disabled");
+    }
+}

calendar/base/content/calendar-recurrence-dialog.xul

@@ -202,11 +202,14 @@
     <label value="&newevent.recurrence.exceptions.label;"/>
 
     <hbox align="center">
-      <listbox id="recurrence-exceptions-listbox" rows="8" flex="1"/>
+      <listbox id="recurrence-exceptions-listbox" rows="8" flex="1"
+               onselect="checkSelectedException()"/>
       <vbox align="top">
         <datepicker id="exdate-picker"/>
         <button label="&newevent.addexceptions.label;" oncommand="addException()"/>
-        <button label="&newevent.recurrence.remove.label;" oncommand="removeSelectedException();"/>
+        <button label="&newevent.recurrence.remove.label;" 
+                id="remove-exceptions-button" 
+                oncommand="removeSelectedException();"/>
       </vbox>
     </hbox>