What is "the latest source"? The 8.6.9 tarball from Sourceforge? That was released last fall.

The commit you are referencing for the changed layout is from July - that's the tip of 8.6 development and will be incorporated into 8.6.10, due out soon.

So, we are in agreement - the rounded look is the new one and the flat look is the older, unsupported version. You are not doing anything wrong. The implementation has changed and will not be rolled back.