Does your book cover the limitations of the GWT, and ways to work around them while still using the GWT? Specifically, I am looking at features like drag and drop, which I last read that GWT didn't support it.
GWT does not yet have built-in support for dragging and dropping Widgets. It has been accepted by the GWT as an enhancement, no word on which release it will be in:
There are ways that you build drag and drop apps with GWT. My book covers the dragging aspect of it in two examples - sticky post-it notes and a mona lisa puzzle.