protected override void OnClick() {
if (_isOpen)
return;
_isOpen = true;
_dlg = new BrowseLayersDialog();
_dlg.Closing += bld_Closing;
_dlg.Owner = FrameworkApplication.Current.MainWindow;
_dlg.Show();
}
void bld_Closing(object sender, System.ComponentModel.CancelEventArgs e) {
_dlg = null;
_isOpen = false;
}