I have some more information on this problem. I only get this error if
my workspace in eclipse is named the same as my GWT project. In other
words, if I create a new GWT project and use the same name for the
project as the name I used for my eclipse workspace, I get the unable
to cast error. However, if I create a new GWT project with a name that
is different than the workspace name then everything works fine. This
means of course that any existing projects where the workspace and the
project name are the same will get this casting error.
Could anyone comment on this? Is it standard practice to keep the
workspace and project names different?