Uncategorized tools would no longer be configurable after first run.

Avoid writing empty string prefixed arrays into settings, and some
isNull vs isEmpty confusion (xml reader seems to read null instead of
empty strings in some cases).

src/plugins/coreplugin/dialogs/externaltoolconfig.cpp

@@ -179,8 +179,9 @@ QModelIndex ExternalToolModel::index(int row, int column, const QModelIndex &par
                 return createIndex(row, 0, items.at(row));
             }
         }
-    } else if (column == 0 && row < m_tools.keys().count())
+    } else if (column == 0 && row < m_tools.keys().count()) {
         return createIndex(row, 0);
+    }
     return QModelIndex();
 }
 

src/plugins/coreplugin/externaltool.cpp

@@ -82,11 +82,14 @@ namespace {
     const char * const kNo = "no";
     const char * const kTrue= "true";
     const char * const kFalse = "false";
+
+    const char * const kSpecialUncategorizedSetting = "SpecialEmptyCategoryForUncategorizedTools";
 }
 
 // #pragma mark -- ExternalTool
 
 ExternalTool::ExternalTool() :
+    m_displayCategory(QLatin1String("")), // difference between isNull and isEmpty
     m_order(-1),
     m_outputHandling(ShowInPane),
     m_errorHandling(ShowInPane),
@@ -318,6 +321,8 @@ static void localizedText(const QStringList &locales, QXmlStreamReader *reader,
             reader->skipCurrentElement();
         }
     }
+    if (currentText->isNull()) // prefer isEmpty over isNull
+        *currentText = QLatin1String("");
 }
 
 static bool parseOutputAttribute(const QString &attribute, QXmlStreamReader *reader, ExternalTool::OutputHandling *value)
@@ -866,8 +871,11 @@ void ExternalToolManager::readSettings(const QMap<QString, ExternalTool *> &tool
 
     if (categoryMap) {
         settings->beginGroup(QLatin1String("OverrideCategories"));
-        foreach (const QString &category, settings->childGroups()) {
-            int count = settings->beginReadArray(category);
+        foreach (const QString &settingsCategory, settings->childGroups()) {
+            QString displayCategory = settingsCategory;
+            if (displayCategory == QLatin1String(kSpecialUncategorizedSetting))
+                displayCategory = QLatin1String("");
+            int count = settings->beginReadArray(settingsCategory);
             for (int i = 0; i < count; ++i) {
                 settings->setArrayIndex(i);
                 const QString &toolId = settings->value(QLatin1String("Tool")).toString();
@@ -878,7 +886,7 @@ void ExternalToolManager::readSettings(const QMap<QString, ExternalTool *> &tool
                     if (categoryMap->value(tool->displayCategory()).isEmpty())
                         categoryMap->remove(tool->displayCategory());
                     // add to new category
-                    (*categoryMap)[category].append(tool);
+                    (*categoryMap)[displayCategory].append(tool);
                 }
             }
             settings->endArray();
@@ -899,7 +907,9 @@ void ExternalToolManager::writeSettings()
     QMapIterator<QString, QList<ExternalTool *> > it(m_categoryMap);
     while (it.hasNext()) {
         it.next();
-        const QString &category = it.key();
+        QString category = it.key();
+        if (category.isEmpty())
+            category = QLatin1String(kSpecialUncategorizedSetting);
         settings->beginWriteArray(category, it.value().count());
         int i = 0;
         foreach (ExternalTool *tool, it.value()) {