void MaterialXMLExportDialog::headerViewDoubleClicked(int logicalIndex)
{
    if (logicalIndex!=0) return;

    allItemsChecked_ = !allItemsChecked_;

    for (int row=0;row<materialView_->rowCount();++row) {
        MaterialTableItem* item = static_cast<MaterialTableItem*>(materialView_->item(row, 0));
        item->setCheckState( allItemsChecked_==true ? Qt::Checked : Qt::Unchecked);
    }
}