@ProphetBeal
I have a second question. There comes an event for each single mail. Wouldn't it be possible to send only one event for all mails together, which of course has parameters that are in nature collections of fileinformations (each element is the data for one mail). From a conceptual point of view, this would be better, because the user's drop action of a multiple selection of mails is one single action (the releasing of the mouse key), so it should result in one single event. Then it would be quite easier to give a message to the user like "your 5 mails have been dropped". In the scenario of one event per mail, how should I decide which event is the last one? Should I wait (using Thread.Sleep etc.) an arbitrary amount of time like e.g. 1000 ms and if no further event comes then I suppose it's finished?