The property panel is empty after switching between a workflow's two views, and clicking the selected step does not bring it back #9400

What happened?

A workflow's two views share one selection. It lives in the root-provided JointGraphWrapper, which the switch between the canvas and the Form View hands over rather than rebuilds — that hand-over is what makes the switch fast.

Nothing is lost in the switch: the step stays selected and stays drawn as selected. What goes wrong is that the panel arriving in the new view never asks what is selected. Both panels that show the selection are driven purely by the highlight streams, with no initial read:

• PropertyEditorComponent.ngOnInit only calls registerHighlightEventsHandler();
• WorkflowFormComponent.syncSelectionFromHighlight() is called only from the highlight and unhighlight subscriptions.

The event that made the selection happened before the panel mounted, so a freshly mounted panel waits for an event that will never come, and shows nothing.

Clicking the step does not recover it either. JointGraphWrapper.highlightElement returns early for an element that is already highlighted, so no event is emitted and the panel stays shut. It takes clicking a different step to make the panel appear, which reads as the panel being lost and the first clicks being ignored.

Observed on a workflow with one step, going canvas → Form View → canvas:

This is not specific to the Form View. The canvas's own property panel is the one that is empty in the last row, and the same gap applies to a selected port, which the panel also serves.

Expected: the panel shows the step that is selected, whichever view you are in.

How to reproduce?

1. Open a workflow's canvas and click an operator: its property panel opens.
2. Switch to the Form View (the tab at the top right): the panel area is empty, although the operator is still selected and still ringed on the preview.
3. Expand the Workflow section and click that same operator: still nothing. Click a different operator and the panel opens.
4. Switch back to the canvas: empty again. Click the operator selected in step 3 — nothing, however many times. Click a different one and the panel opens.

Reproduced in both directions, every time.

Version/Branch

1.4.0-incubating-SNAPSHOT (main)

Commit Hash (Optional)

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What browsers are you seeing the problem on?

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Relevant log output