Thanks @jeremyruston. I just confirmed that in prerelease 4 I see all the problems I reported (river-open tab mismatch, can create but not close 1 tiddler, can’t open a second tiddler- either new or existing, “ghosts” in the river that seem like just the top and bottom margins of the display of a tiddler but nothing else, …) I don’t see these problems in prerelease 3.
A concrete example is that GettingStarted is there in the river when I open the fresh wiki (empty tiddlers folder). If I just try to close it immediately, it closes but if I create a tiddler first and then try to close GettingStarted it remains in the river- though it does get removed from the open tab and when I open the StoryList tiddler in TextEdit GettingStarted has been removed from it- so that does match the open tab). Happens in prerelease 4 but not prerelease 3.
I just looked in the tiddlers folder of my test wiki (running prerelease 4) after trying to create and rename some tiddlers and it seems to reflect the creating and renaming that I have done. It is hard to get exactly the same result twice but at the moment I have a new tiddler open in edit mode. I can type a new title for it and clicking the save button saves the updated tiddler to the tiddlers folder but it does not leave edit mode in the river and still says above the title that it is a draft of new tiddler. If I now click the plus to create a new tiddler it replaces the “renamed” tiddler with a “New Tiddler” draft in the river. The open tab shows both the renamed and the new tiddler as being open.
Ok, I seem to have gone down a debug rabbit hole. I hope there is something in this that gives you an ah-ha moment.
I don’t know about CSS tweaks. Given the behavior I’m seeing, I don’t even know how I would test that.