Trees have become less usable in Firefox "lately"—especially there seems to be an increase of "jumping" issues.

When using inplace-editing below the fold (in config-app)

• hitting ENTER on property names or property values abnormally centers the selected row [1]
• hitting ENTER on a node name scrolls back to the top
• hitting ESC scrolls back to the top
• hitting TAB doesn't jump at all

When using the context menu below the fold (via sang.ngo, thanks for reporting)

• Right-clicking an unselected row abnormally centers that row [1]
  • Clicking aside to close it scrolls back to the top
• Right-clicking a selected row doesn't jump at all

notes

• Chrome now doesn't suffer the same symptoms
• I could reproduce it also on 5.4.6, so it is well possibly caused by a change in recent Firefox versions, rather than inside the UI framework or Vaadin.

[1] I suspect the RowScroller to come into play here somehow

Update 2016.12.28

Chrome now suffers as well from scrolling back to top, albeit slightly differently:

• hitting ENTER or ESC in inline-editing (TAB also doesn't jump)

upon any "indirect selection changes",

• e.g. adding nodes, properties (unlike FF)
• Right-clicking an unselected node (unlike FF's "centering effect")