GraphExplorer and its Demo project are now compilable and executable.

But not works correctly.
The GraphExplorer and its Demo are workable again.

Test project still not compilable
GraphExplorer's folders structure reorganized
Created some blank classes for using MVVM pattern
FilePicker 90% refactored
ToolBar half finished
ToolBox renamed to ToolBar
TaskBar reorganizations is stopped. The first stage of the Views  refactoring are finished. Now it's ViewModels's turn.
GraphArea.LogicCore now binded from the ViewModel. EdgeControl and VertexControl are moved back to the view.
OperationObserver moved from the ViewModel to the Model
Drag and drop almost implemented using behaviors. Created ViewModels for ZoomControl and GraphArea
Drag and Drop works. GraphArea behaviors must to be created. Need to refactor all operations with graph.
the logic of Graph editing is partly moved to the separated service
All behaviors are moved to each own classes. Ready to create custom vertexes and edges with own ViewModels
implemented custom GraphControlFactory. Created views, viewmodels and models for edges and for vertexes. But not all logic properly organized yet.
has been created new project GraphExplorer, which will be used instead of the old one. This probably makes the reorganization process much easier.
graph loadable but not uses control templates.
Used template for the VertexView. Triyng to use View, ViewModel and Model for the properties of the vertex.
MVVM implemented for GraphArea, edges, vertices and properties. But not all logic migrated yet.
Removed custom zoomcontrol. Created universal Toolset control, which will be used for editing, navigating and filtering