Editor in dialog overlapping another breaks SideMenu and drag-and-drop

What’s broken?

We have a setup with an editor and a button next to it that opens another editor instance in a dialog above it. In areas where the two editors directly overlap, the SideMenu does not appear in the topmost editor. Drag and drop is also not possible in these overlapping areas.

https://github.com/user-attachments/assets/be553b97-812c-487e-9f84-7aa12d7f9e20

The root cause is likely in findClosestEditorElement (in SideMenu.ts) because it does not consider the z-axis stacking order when determining the editor element.

What did you expect to happen?

Option 1
Ensure Sidebar and drag-and-drop interactions only consider the topmost editor.

Option 2
Add an option to exclude specific editors (for example editors behind a dialog) from the hover and drag detection logic.

Steps to reproduce

Having an editor in a dialog above another editor

Demo:
https://react-shadcn-blockno-nf9x.bolt.host

BlockNote version

No response

Environment

No response

Additional context

No response

Contribution

• I'd be interested in contributing a fix for this issue

Sponsor

• I'm a sponsor and would appreciate if you could look into this sooner than later 💖

Start in packages/core/src/extensions/SideMenu/SideMenu.ts at findClosestEditorElement, then reproduce the overlapping-editor case using the linked demo. Trace how SideMenu hover detection and drag-and-drop choose an editor; done means the topmost editor handles both interactions without breaking ordinary editor behavior.