I know this is probably trivial to most, but it's really bugging my client. I can reproduce this in just about every install I have...after the initial install, and after you make a modification the first time...the Tree item stays green. I've tried everything, and it will always stay green.
It will always be green as SS 2.4 + workflow introduced a great feature as if it doesn't detect any changes to the page then it won't create a new version or publish it. But for UserForms I haven't got round to building change detection as it involves a number of components.
If anyone wants to get stuck into fixing it I would be most grateful. The specific function is https://github.com/silverstripe/silverstripe-userforms/blob/master/code/UserDefinedForm.php#L282
You could change this to return false and it will stay black (instead of green) https://github.com/silverstripe/silverstripe-userforms/blob/master/code/UserDefinedForm.php#L282.
If anyone has the time to get the detection working would be good to have, it'll have to track form field updates, setting changes (could just use a parent:: getIsModifiedOnStage() for that) and email submission updates (which aren't versioned) against the latest published date.