QDrop event is cant be accepted outside application

I have a widget running as an application. The widget is a container containing widgets. Those implement a drag functionality and accepts drops. I started 2 instances of that application and tried to drag from one application to another. When I drop on another application everything goes fine. But when I return mouse cursor to the first application it seems, that drag execution has not finished yet. That isn't cursor drawing problem but drag execution really continuing.