Hi, don't you get nice red-cross when opening a browser and selecting comment? (Pharo7.0-32bit-b5ec533.image) The problem is LayoutFrame having a Point instead of Number in fraction/offset inst. var. So I defined two horrible hacks in order to be able to work with Pharo Point>>@ n ^x @ n Point>>asInteger ^x asInteger then could instrument the LayoutFrame inst. var. setters with horrible checks like: aNumber isNumber ifFalse: [ self halt]. And after a few seconds of IDE usage: AbstractNautilusUI>>buildCodePanelWithCommentOnRight ...snip... sourceCodePanel addMorph: commentWidget fullFrame: (LayoutFrame identity leftFraction: 0.5@0 ; leftOffset: delta). Huh! it's as pleasant as not eating own dog food I think this comes from a recent refactoring. I can hardly use in image tools to trace it. Iceberg bugs, MC has lost ancestry and is just good at synchronizing disk working copy with image working copy, but there is github & git API: https://github.com/pharo-project/pharo/commit/042baad47fddb63db2dd0beefeec69... As it's nearly impossible to make giant refactorings like this without human error, and as it's as impossible to review pull request with many lines of code, I wonder if it is possible to automate those with rewrite rules... I let you finish the work (open issue, patch, commit, etc...)