I meant to report this months ago as it's been in the whole 4.0.* line I think. Still present in the latest 4.0.8 (from git).
1. Click a table name to browse it.
2. Click "Edit" on the SQL query box (i.e. next to Inline, Explain SQL etc)
3. In the popup window, click the SQL History tab.
4. Click the edit icon next to a query.
Expected: A page like the SQL tab to appear with the appropriate query in the textarea.
Actual: Basically a blank page. There is just one checkbox with the label "Do not overwrite this query from outside the window" and nothing else.