Mumfrey, there's also this strange issue I face on the 1.11.2 version, as I did on the 1.8 version of Macros. Switching from the chat screen to the main screen always makes my custom GUIs hop about. Icons are constantly cut off and text is constantly elongated in the main screen, but they are fine in the chat screen. Here's an example:
In the video I also will demonstrate a bug with the rightmost column of the GUI editor where it can't be automatic.
Different GUI slots have different padding, you can change the padding of the slots if you want by editing the .gui.xml
The last column being different size is just a side effect of how the colum widths are calculated. In order to avoid weird rounding errors the columns are clamped to certain width increments, the last column just takes up the "spare" space to fit the screen. It's not a bug that's intentional.
You can turn off highlighting in the editor box if you don't want it.