It would be nice to be able to collapse (0 height) the structure pane, but have the handle available for quick viewing, instead of enabling/disabling the structure windows via menu. The same as the favorites pane acts now. Reproducible: Always Steps to Reproduce: Enable Message Structure Drag pane divider down Actual Results: Pane has minimal height, stays visible Expected Results: Would be nice if could be collapsed (0 height, only drag handle visible like favorites window)