You will find when editing these files that there is a lot of ClipView which needs to be sorted before you can do any editing. The easiest way to proceed is to use Alt+Q and then Ungroup if required Ctrl+U. Good luck if you want to edit these files. I wouldn't say that you are going to across too many not closed shapes but lines that surround closed shapes must be dealt as individual parts of the shape whichs not the way Xara products work they tend to be the same part of the shape. Just delete the line and give the closed shape a line thickness.