As you can see, after the first click on the expander button, block does not expand, Instead of that the whole area scrolled a little. After that everything works just fine with any position of scrollbar and you can expand and collapse any block.
Can you help me with this issue? I have no idea what it can be connected with. Maybe there is some information I should provide for you?
How did you initialize your diagram? Besides setting properties on the Diagram, including templates, did you create a model and assign Diagram.model? Is there anything else that you did afterwards?
I don’t do any specific things afterwards, but maybe it will help you: the problem occurs only if graph has height more then screen can contain. So, the way to reproduce the bug is
draw graph with big height
scroll page the way just top part of the graph is on the screen
click anywhere outside the graph (just for losing focus)
click anywhere inside the graph
The easiest way to reproduce is to set height of the div.diagramStyling in the first example (click counter) on this page to 3000px and go through all the steps.