In my code’s mouseDrag(), I’ve noticed I’m using the delta mouse position (x or y) very often, which is the x or y difference since the last mouseDrag call. Maybe one could add this to as MouseEvent::getDragDeltaX(), MouseEvent::getDragDeltaY() ?
Strange that I’ve never needed that! Good request though, I guess it’d come in handy when you’re using the unbounded movement mode.
Yes, it practically only makes sense to use it without any visible mouse pointer. For instance, for a vertically-dragged Slider: When you drag up or down, depending on the situation it’s not good to take the absolute drag distance y, but better to take the delta distance, because if the range of the slider is 100 pixels, and you drag the mouse up 200 pixels far (slider goes up until reaching the top), you’ll have to drag it 100 pixels again until you notice change (slider going down again).