diff --git a/kcmkwin/kwintabbox/layoutpreview.cpp b/kcmkwin/kwintabbox/layoutpreview.cpp
index 6af3cc6251..6430bbfdc3 100644
--- a/kcmkwin/kwintabbox/layoutpreview.cpp
+++ b/kcmkwin/kwintabbox/layoutpreview.cpp
@@ -170,6 +170,18 @@ QVariant ExampleClientModel::data(const QModelIndex &index, int role) const
     return QVariant();
 }
 
+QString ExampleClientModel::longestCaption() const
+{
+    QString caption;
+    for (QString item : m_nameList) {
+        QString name = KDesktopFile(item).readName();
+        if (name.size() > caption.size()) {
+            caption = name;
+        }
+    }
+    return caption;
+}
+
 int ExampleClientModel::rowCount(const QModelIndex &parent) const
 {
     Q_UNUSED(parent)
diff --git a/kcmkwin/kwintabbox/layoutpreview.h b/kcmkwin/kwintabbox/layoutpreview.h
index 7db9a07e9f..0203909eda 100644
--- a/kcmkwin/kwintabbox/layoutpreview.h
+++ b/kcmkwin/kwintabbox/layoutpreview.h
@@ -53,6 +53,7 @@ public:
 
     virtual QVariant data(const QModelIndex &index, int role = Qt::DisplayRole) const;
     virtual int rowCount(const QModelIndex &parent = QModelIndex()) const;
+    Q_INVOKABLE QString longestCaption() const;
 
 private:
     void init();