Stop-Limit orders look a little different on DOM display. The order has two prices - a Stop price and a Limit price.
The capsule is placed at the Stop price of the order. It also has an arrow that points to the Limit price of the order. Once the Stop is hit, the order is converted to a Limit order, and the capsule on the DOM display is changed accordingly.
As with other order types, you can change the Stop price of the order by dragging the capsule.
To change the Limit price, though, you should drag the arrow that points to the limit price. Note that in the example above, the modified order capsule overlaps the old (sent) order capsule because the Stop price of both is the same.