Not sure if that's not something that should be fixed upstream in WebKit.
Pierre said: "Not sure if that's not something that should be fixed upstream in WebKit". That is exactly my opinion. So, as Pierre knows about this surely better than me, I'll let him decide where this has to be merged :)
Actually, this should work out of the box in QtWebKit 2.2, and doesn't for rekonq. The proper fix would probably to investigate why. Note that dragging text in the middle of a text field will be hard to do with your approach, so I'd say r- for now, since the problem is elswhere it seems.