The browser is covering the Brain panel

Nothing is broken. The preview browser is drawn on top of codus rather than inside it, so when the Brain panel slides open or shut, the browser can be left sitting at its old spot for a moment and cover the panel. To put it back, click the web button in a quadrant's header off and then on again. The browser is placed fresh and lands where it belongs.

The quickest fix

In any quadrant's header there is a web button with a small globe. Click it to hide the browser, then click it again to reopen it. Reopening places it correctly.

This is better than dragging anything, because it does not change your layout.

Another way

Switching to a different area and back also fixes it. Click any other tab along the top, for example Settings, then click back. The browser is re-placed as the view loads.

If you would rather drag

Dragging any panel edge also snaps the browser back into place, because moving an edge forces codus to reposition it. The Brain panel has its own drag handle on its left edge. This works, but it nudges your layout, so the web button above is the cleaner fix.

How do I know it worked?

The browser sits inside its own pane again and the Brain panel is fully visible.

Why it happens

The preview is a real browser that the operating system paints over the top of everything codus draws. When a panel slides open, codus does not always tell the browser its new position in time, so for a moment it stays where it was. It is cosmetic, and any of the fixes above sorts it. It is on our list to stop happening on its own.