Docking window does not remember width when app window is maximized

This occurs when resizing the docking window (application window is maximised).

You can resize the docking window fine, after the docking window slides in (auto-hide). When you reopen it its width is the same before you had resized it.

Ive noticed that when the application window is not maximised that the docking window remembers the changes.

Any ideas?

Cheers