Gets if the document line is collapsed.
This property initially is true and turns to false when uncollapsing the section.

Assembly: ICSharpCode.AvalonEdit (Module: ICSharpCode.AvalonEdit.dll) Version: 5.0.0.4238
Assembly: ICSharpCode.AvalonEdit (Module: ICSharpCode.AvalonEdit.dll) Version: 5.0.0.4238