To insert a row, right-click a sample in the sample column and select Insert Row Before from the shortcut menu.
To delete a row, right-click a sample in the sample column and select Delete Row from the shortcut menu.
To insert a column, right-click a signal in the signal column and select Insert Column Before from the shortcut menu.
To delete a column, right click a signal in the signal column and select Delete Column from the shortcut menu.