LineStyle dialog should have a Filter combobox on the top of the list to filter according to:

• Used styles (although we can do this from Element Selection if previously we "select all")

• styles of the drawing.

• styles not used (if we use the Compress option) those styles would be erased.. Even we could remove them from here.

• All

Also it should have an icon next to the name if that style is used or part of the drawing (was active in some moment).

LineType Manager in AutoCAD has a filter to filter the list of styles..