Changes since https://issues.apache.org/jira/browse/HARMONY-5949
-WarningLogDialog class to display and store the warning and error messages.
New feature (compared to Sun's policytool): the warning log dialog is non-modal which is a lot more useful here because we support
direct editing, and switching between the editor panels can generate errors/warnings frequently (not just when opening a new file or
validating form values).
The warning log can be open while we edit the policy text in any editor.
If we use the "View warnign Log" menu while it's visible, it will be centered again.
-Fixed a bug where permission signedBy caused a parse exception.
-Validation to form dialogs.
-Fixed the following bug: If we edit an item of a ListAndEditPanel, we change it in a way that its toString() method will return
a very long string (long as it won't fit in the displayed width), its string will be truncated (ended with "..."),
and no scrollbars will be displayed.