Add possibility to save/restore WebDocumentPane state

[mgarin]

At the moment WebDocumentPane state cannot be easily restored without additional efforts and coding. There should be a way to save and restore documents positioning within the pane.

Original issue:
http://weblookandfeel.com/forum/viewtopic.php?f=4&t=203

[mgarin]

Starting with v1.29 it will be possible to save/restore WebDocumentPane state.

There are several options to do that, you can retrieve/set state manually:

final DocumentPaneState state = pane.getDocumentPaneState ();

pane.setDocumentPaneState ( state );

Or simply register your WebDocumentPane in SettingsManager, for example:

pane.registerSettings ( "DocumentPaneTest", "state" );

This will save your WebDocumentPane state in a separate settings group automatically on changes (unless that option - autosave on changes - is switched off). You can also force settings save action:

pane.saveSettings ();

Though that will work only if you have already registered your WebDocumentPane in SettingsManager.

One more important thing about this feature - in case you are restoring the state - you might want to have all documents be already opened at that moment or set DocumentDataProvider into your WebDocumentPane, otherwise state won't be able to restore document locations properly.

Here is an example how you can set DocumentDataProvider:

pane.setDocumentsProvider ( new DocumentDataProvider ()
{
    @Override
    public DocumentData provide ( final String documentId )
    {
        return new DocumentData ( documentId, ... );
    }
} );

Basically this provider can replace manual documents open process and will do that on its own. Though it is up to you to choose how you want to do that part.

All these changes are already available in sources and will be included in v1.29 release.