Own FlashMessages

Is there a reason why a datagrid doesn't render its own flashmessage? Sometimes I render more grid on one page and flashmessage on presenter are less user-friendly.

My usecase for example:

class ItemPricesGridFactory
{

	public function create(Item $item): \Ublaboo\DataGrid\DataGrid
	{
		$grid = new \Ublaboo\DataGrid\DataGrid();
		// add cols…

		$grid->addGroupAction('Synchronize')->onSelect[] = function (array $itemIds) use ($grid): void {
			// some process…
			$grid->flashMessage('All is OK'); // now I use $grid->getPresenter()->flashMessage()
			// redirect/redraw…
		};

		return $grid;
	}

}

I can not send PR because I do not know how to do it nicely in css and js.

Start by tracing the DataGrid flashMessage() and getPresenter()->flashMessage() usage shown in the issue, then inspect the existing grid rendering and frontend behavior. Define how a grid-owned message should appear when several grids share a page, including the required CSS and JavaScript behavior; done means the message renders in the intended grid context after the group action.