Tree stops functioning after calling grid.set('columns', columns) with previous columns

[kriszyp]

This is very easy to reproduce, once you have created a tree grid, simply set the columns again with the same columns:

treeGrid.set('columns', treeGrid.columns)

And you will no longer be able to expand nodes. I reproduced it on common_cases.html with the tree grid there.

The cause of the issue is that the tree column will set _isConfiguredTreeColumn to true. When you later reset the columns, _destroyColumns will remove the expando listener. When the columns are reconfigured, _configureTreeColumn will be properly called, but will immediately return because _isConfiguredTreeColumn is still true, so the listener will never be re-added. Also, _treeColumn is nulled in _destroyColumns, and won't get reset by _configureTreeColumn, so even if expand does get called, it will immediately return as well because _treeColumn isn't set.

This is actually a regression due to:
26a6d00

Prior to that commit, _configureTreeColumn properly scoped the column configuration code inside the conditionally branch of _isConfiguredTreeColumn, and properly re-added the listener and _treeColumn when tree columns were reconfigured.

I could put together a pull request, but clearly the regression commit was trying to accomplish something, so I thought I would start by just identifying the exact cause.

[kfranqueiro]

Thanks for reporting this, Kris. In 0.4.1 / 1.0.0, we had a couple of fixes in that area having to do with avoiding redundantly hooking up renderCell and event handlers, but it looks like at some point we oversimplified. I think it slipped my mind that those event handlers were in fact being removed in _destroyColumns.