Wrong diagram palette position when multiple diagrams are open (in a portal)

[pcdavid]

Steps to reproduce:

1. Create a portal
2. Place 2 Topography diagrams beside each other in the portal
3. Click on the background of the diagram on the left
4. The palette opens in the second diagram

See the video below:

Capture.video.du.2024-01-29.10-38-28.webm

[pcdavid]

I think this is caused by:

const wrapperRef = document.querySelector('.react-flow');

in PalettePortal.tsx, which assumes there is a single .react-flow element visible at a time.

When N diagrams are visible at the same time, document.querySelectorAll('.react-flow') returns N elements, but we use querySelector and get whichever is the first one returned.

[pcdavid]

Note that in DiagramRenderer.tsx we already get the actual React.Ref<HTMLDivElement> we need.