Detached DevTools window in vivaldi is both decorated and not

[galtgendo]

If you open DevTools window in vivaldi it looks decorated, but mouse doesn't interact with the decorations, to the point where with 'focus-follows-mouse' moving the mouse onto the titlebar makes the focus move to the window below the dialog.

I've asked other people about it and they've reproduced it, checked it doesn't happen in fluxbox and doesn't happen in a couple other chrome based browsers (like firefox).