The current implementation of SessionStorage.getComponentPathname is inflexible
and buggy.

Why inflexible:
The component passed to the save/ restore methods might have a different parent
hierarchy when restoring it than it had when it was saved. With the current
implementation, which is dependent on the parent hierarchy, the stored session
information will not be found anymore, because the calculated name is different,
in this case.


Why buggy:

while((c.getParent() != null) ...) {
c = c.getParent();
...
int n = c.getParent().getComponentZOrder(c);

While tested if c.getParent() is not null,
c.getParent().getParent().getComponentZOrder(c) still throws a
NullPointerException, if c.getParent().getParent() is null.

This situation arises if a component is passed to save/ restore, whose top most
parent is not a Window, not an Applet and has no name set.

Proposed solution:
Since only one component tree is stored per file, there is no need to include
the parents of the root component in the name as well. So when calculating the
name from the parent hierarchy just stop if the passed root has been reached.

Note: It should also be possible to avoid to recalculate the name of the parents
eg. by using a Stack.