When a hard page is dragged and the mouse is released outside the Book range, there are flipping animation issues: We start flipping the first (hard) page by clicking with your Mouse in the PageFoldArea. Holding the mousebutton we move the page over the middle of the book and outside of the books rectangle we stop holding the mouse button - the currently flipped page remains at the position it is, instead of completing the flipping process (although we released the mousebutton)… Then we can move the mouse to the right upper corner of the next right page… … move the mouse in the pagefoldarea and (before the hard page terminates its flipping process) click on page with index 2. Now the strange behavior starts. The book pages are now incorrectly displayed. If then you click on the right bottom page fold, parts of the coverpage suddenly reappear… At a certain point the book control cannot be used than anymore.