Hello. I wonder if Toolbar Contribution is provisional in pure e4 application? I had a known issue with HandledToolItem and visibleWhen CoreExpression (https://bugs.eclipse.org/bugs/show_bug.cgi?id=400217), so I decided to use a workaround suggested in the last comment to the bug - adding HandledToolItems to a Toolbar Contribution. Now CoreExpressions are working as intended, but everything else is broken. For example, I try to programmaticaly change HandledToolItem's tooltip or "selected" attribute for a "checked" item, and it yields no effect.