The biggest remaining issue that I am aware of at moment is when trying to resize a column if there is grouping. The presence of the grouping seems to cause the widths to go change is bizarre ways.
I committed a small fix. This works on a wide variety of cases that I have. However, on occasion, if I press search and manipulate the columns, sometimes, I can see some wonky behavior, but I can't quite place it. Sorry for all of the iterations, but it's a pretty big change underneath.
Do you think there is anything stopping me from merging this pull request? As far as I can tell (with the limited testing I have available), there are no major issues and it is already better that what is there now. If there are any issues, I will try to fix them quickly.