This is implemented in ProbeSetDataGrid subclass, but maybe better in the base class.
<rdar://problem/16005948>
I had some column addition code but wasn't too sure whether it did the right thing or not. I ended up refactoring DataGrid so that it's much more obvious that adding columns incrementally is correct. See changelog on patch for details.
Created attachment 223415 [details] patch
Comment on attachment 223415 [details] patch View in context: https://bugs.webkit.org/attachment.cgi?id=223415&action=review > Source/WebInspectorUI/UserInterface/DataGrid.js:336 > + for (var [identifier, column] of this.columns) Sweet!
Comment on attachment 223415 [details] patch Clearing flags on attachment: 223415 Committed r163637: <http://trac.webkit.org/changeset/163637>
All reviewed patches have been landed. Closing bug.