I don't trust dragging order "lines" on charts. Maybe there's a setting I'm missing... but often times the "scale" of the chart along the y-axis changes while I'm in the middle of dragging -- which makes it unnerving to actually release the mouse button. I would not recommend doing this for a security that wasn't highly liquid with a tight bid/ask spread.
It cost me some money, yeah. I got used to it. Just be careful on the release. Your order doesn't change until you release. I find a trackball is a little more accurate than a mouse or touchpad. I am thinking that a gaming joystick would be good, actually. Haven't tried that yet. You can also just click on the order and then use the up and down arrow keys to move it. Then use your "Transmit" or "Update" hotkey as appropriate.