Comment 43 for bug 859474

As I've said on the Launchpad bug report:

There are more actions than just the dragging action that require the left mouse button to be held down. There's also the up and down arrows on scroll bars, or numerical input widgets with up and down arrows. To simulate holding down the left mouse button you are supposed to (Tap) + (Press and Hold). When holding the button down on the mouse to keep a button on screen pressed by the cursor, you are obviously not supposed to drag the mouse around. By extension, dragging itself shouldn't be initiated by dragging the finger, the drag should be initiated by the simulated holding down of the left mouse button, which should be the (Tap) + (Press and Hold)