I can drag and drop nodes on the palette. When I drop a node with long name (text block in NodeTemplate), the node is shrink so that the whole name can be shown on the palette. How can I prevent this? I don’t want to resize the node. I want to stick with the default size I set on the Node Template.
It sounds like you are not talking about the resizing of a Node, neither by the user via the ResizingTool nor by setting its Width and Height, but about its being scaled so that it looks smaller. Is that a more accurate description of the situation?
If so, have you set Diagram.InitialStretch or Diagram.Stretch (or the same properties on DiagramPanel)? That would cause the whole palette diagram to be auto-scaled, either initially or all the time.
Have you considered causing the TextBlock to wrap, so that the node doesn’t become so wide due to a long string?