in reply to Tk::AbstractCanvas problem

Is it somehow possible to restrict the minimum size of a node (Tk::GraphItem::TextBox) in the AbstractCanvas.

Sure, but I think you'd have to patch the module :)

Or maybe you could create a Scrolled Canvas and set/enforce the minimum size to something acceptable

How can I make a small view of my whole Graph Layout window which I can use as a control widget to navigate the main layout (This widget may be placed at some corner of the same frame or may be independent).

create two canvases and place one on top of the other, see Tk-AbstractCanvas-1.4.A7QFZHF/ex/ , its close enough