QtQuick.Controls 2 Dialog with content gets wrongly positioned when applying enter-Transition

A Dialog, on which the position in animated in the enter-Transition shows misbehaving positioning, with the wrong content, e.g. a simple Button.

See the two attached files.

The difference is, that in the workaround, the button to close the dialog is wrapped in an Item that fills the Dialog. If this Item is removed and only the Button remains, the Dialog won't be positioned at 150/150, as the enter-Transition dictates. Instead it will flicker and appear at 0/0.

See also: https://stackoverflow.com/questions/49997002/how-can-i-animate-a-dialog-to-enter-from-outside-the-screen