test.cs

private void FormatSelectedTableCells(TableCellFormat cellFormat)
{
	Table table = textControl1.Tables.GetItem();

	if (table == null)
		return;

	Selection curSelection = new Selection(
		textControl1.Selection.Start,
		textControl1.Selection.Length);

	// Clear the current selection
	textControl1.Selection.Length = 0;

	// Determine the starting row and column
	TableCell tableCellStart = table.Cells.GetItem();
	int startRow = tableCellStart.Row;
	int startCol = tableCellStart.Column;

	// Set the selection to the last cell in the selected range
	textControl1.Selection.Start = curSelection.Start + curSelection.Length - 1;

	// Determine the ending row and column
	TableCell tableCellEnd = table.Cells.GetItem();
	int endRow = tableCellEnd.Row;
	int endCol = tableCellEnd.Column;

	// Loop through the selected range and apply formatting
	for (int row = startRow; row <= endRow; row++)
	{
		for (int col = startCol; col <= endCol; col++)
		{
			TableCell cell = table.Cells.GetItem(row, col);
			cell.CellFormat = cellFormat;
		}
	}
}