I really miss the possibility to move the pop up window around the screen from a web map or web app. The pop up window very often covers most of the feature you have clicked on. It would be good to be able to move the pop up away so that one could see the selected feature without interference. This applies particulary when you have cliked on a number of features and have to scroll through the list in the pop up. It is hard to see which feature is selected when the pop up is covering it.
This idea has been merged with Movable popup window in ArcGis Online.