FOSS gamedev and creative worlds

This seems like it's always been a problem, but I thought I'd look into it. Anyone have any idea what causes this?

Here's a screenshot of what I mean:



A nice sunny day, and right in the middle of this patch of green (where there is no floating island or anything of course) is pitch black.

There was a bug a while ago, where saplings caused this. Just plant another sapling and let it grow to a tree to fix the shadow.

In my experience, the only workaround for this problem is to create a roof and then remove it. The easiest way is to use worldedit and then create two blocks for the corners of the roof. Then //p set, //set dirt, //set air and the lighting gets forced to update below. Why you would need to do that I have no idea.