Design Patterns

Could anybody tell, what type of design pattern can be used for Samples>FlowCharter like application.

I don’t know how to answer this question. Could you ask it again in a different manner, or could you ask a more specific question for what you want to be able to do?

Apart from the document-view architecture, can you suggest me any of the GOF design pattern that can be used to build an application like the Flowcharter sample.

If you are asking what design patterns GoDiagram uses, I can give a quick list:
Observer: GoDocument.Changed event and GoChangedEventArgs, observed by GoView. Also there are a bunch of GoView events. And in a multi-tier document/view structure, you might maintain your GoDocument by observing your lower level data structures, if any.
Composite: grouping of GoObjects in GoGroups
Factory: constructing GoObjects in GoDocuments from your data
Command: undo-redo using GoChangedEventArgs
State: IGoTools used to implement mode-like behavior by handling input events for GoViews
Visitor: GoXml’s framework for reading/writing customized XML based on existing GoObject structures
Iterator, Template et al as in any .NET application
There are probably some others that I missed as I was scanning through the list of patterns.

Great, Thanks for providing the list of the patterns used by GoDiagram.