private void menuItem_AddToPreviousCollection_Click(object sender, EventArgs e)
        {
            ListViewItem lvi = listview_Textures.SelectedItems[0];

            System.Diagnostics.Debug.Assert(lvi != null);
            Editor.TextureCollection collection = GetTextureCollection(m_collection_added_to);
            collection.AddTexture(lvi.Text);
        }
        private void menuItem_AddToCollection_Click(object sender, EventArgs e)
        {
            if (listview_Textures.SelectedItems.Count > 0)
            {
                ListViewItem lvi = listview_Textures.SelectedItems[0];
                System.Diagnostics.Debug.Assert(lvi != null);

                Editor.TextureCollection collection = editor.TextureCollections.Find(c => EscapeAmpersands(c.Name) == ((MenuItem)sender).Text);
                collection.AddTexture(lvi.Text);
                m_collection_added_to = collection.Name;
            }
        }