Removes the obsolete handleColumnHighlighting() method which causes a significant performance hit when rendering a datatable with many rows.
Column width and row highlighting is now handled by CSS so this method should no longer be needed.
The 'give all values consistent width' part of handleColumnHighlighting() is the real performance hit, adding mouse event handlers to add/remove classes doesn't really impact loading speed. So I've restored the method and tested again with just the width setting code disabled and performance is basically the same as with the handleColumnHighlighting() method disabled.
This means the ratio values will work and any other code that relies on the column highlight class being set.
@sgiehl Following the theme of naively deleting random datatable functions... :wink:
I've committed this change for review and it seems to work well in the tests I've done. Can you think of any problems with this approach or anything I should specifically test?
I've updated all the screenshots for UI tests that failed from this change.