private void contextMenuEntry_ItemClicked(object sender, ToolStripItemClickedEventArgs e)
        {
            switch (e.ClickedItem.Text)
            {
            case "Edit":
                FormCreateEntry f = new FormCreateEntry(this, selectedEntry, selectedEntity, attributes);
                f.ShowDialog(this);
                break;

            case "Delete": DeleteEntry(selectedEntry); break;
            }
        }
 /**
  * Show dialog to create entry.
  * */
 private void btnAddEntry_Click(object sender, EventArgs e)
 {
     if (f == null)
     {
         btnSaveFile.PerformClick();
     }
     else if (entities.Count == 0)
     {
         MessageBox.Show("Please create some entity with attributes :)");
     }
     else if (selectedEntity == null)
     {
         MessageBox.Show("Select entity");
     }
     else
     {
         FormCreateEntry f = new FormCreateEntry(this, selectedEntity.Name.Trim(), attributes);
         f.ShowDialog(this);
     }
 }