Select Fill Columns in the Block menu to fill a rectangular block with one or more characters. If you enter less characters than the width of the selection, the characters you entered will be repeated on each line as many times as necessary. If the number of selected columns is not an integer multiple of the number of characters you entered, the last repetition of the inserted characters will be truncated at the last selected column. The same characters will be inserted on each line.
If some of the lines already had text in the selected columns, that text is overwritten by the filled block. If some of the lines were shorter than the selected columns, spaces will be inserted to extent those lines until the filled block.