Moving elements onto breadcrumb blow up editor

[nikku]

Describe the Bug

If I accidentally move an element over the newly introduced breadcrumbs the editor blows up:

Steps to Reproduce

1. Drill down into collapsed process
2. Move sub-process contents onto breadcrumb
3. See editor blowing up (not recoverable)

Expected Behavior

Two options: Move is rejected or, even better, breadcrumbs are ignored during dragging (pointer-events: none).

Environment

• Browser: any
• OS: any
• Library version: bpmn-js@next (develop)

[nikku]

@marstamm Are you already aware of this one? If not, let us add it to the list of our TODOs.

[nikku]

With #1506 closed we should give this another look, shall we @marstamm.

[marstamm]

I think this is a general problem with the viewer. You cannot move elements (on the breadcrumbs or otherwise). This

bpmn-js/lib/features/auto-resize/BpmnAutoResizeProvider.js

Lines 36 to 40 in cd31ef4

	// do not resize plane elements:
	// root elements, collapsed sub-processes
	if (is(target.di, 'bpmndi:BPMNPlane')) {
	return false;
	}

is the fix we need and it will be integrated with #1536

[nikku]

Note that we've solved it for the palette already; we shall aim for a similar fix, UI wise: