Hi,
I'm the current maintainer of Mappy addon. Its main feature is the square shape of the minimap.

I've received a bug report recently asking me to add support for MBB, which I did, but in the process I've noticed that MBB does not respect Mappy's square shape. It moves in a circle, respecting only Mappy's size, but not shape. Mappy is not doing anything to addon buttons in this configuration, so it doesn't seem to be at fault. I've quickly looked at MBB's code and didn't find anything related to shapes, so I think it's MBB that doesn't support other shapes than default blizz circle.

Mappy and many other minimap addons are providing a global GetMinimapShape() function that can be used by other addons to calculate how the button should move to still respect the minimap's shape. Libraries dedicated to generating buttons have this functionality already baked in, they check for GetMinimapShape() automatically. One such library is LibDBIcon-1.0.

If you decide to support square minimaps, I think the best approach would be to just use LibDBIcon to generate MBB's icon. I saw an issue requesting exactly that, could kill two birds with one stone - #23

I'm ofc ready to help and discuss this further. I might have misunderstood how MBB is doing its thing (I'm bad at reading XML lol). But I really think it just doesn't support square stuff.

If you want to reproduce this on your end:

1. Download Mappy version 4.5.2b (beta release) - https://www.curseforge.com/wow/addons/mappy-continued/files/4095698
2. Go to Mappy options (/mappy), open Buttons tab, disable "Auto-arrange addon buttons".
3. Move MBB icon - it will move in a circular motion, ignoring the minimap's square shape.

Example addon that uses LibDBIcon to generate their buttons - BugSack (it requires BugGrabber to be installed as well)

There are a few comments under Mappy about this issue, if you want to read them.