New outer scroll bar appears when function is moved to another file

Those two were supposed to be rendered identically :

Method :

1. I created the v1 folder that works perfectly, it is just one main.c (plus the nk files), it has a `void render_widget_list(struct nk_context **ctx, int win_width, int win_height)` that renders a list widget

2. Then I created the v2 folder as a copy pasted one from the v1 and just moved the exact same `render_widget_list` function to another file `gui.c` (with its `gui.h` header file)

Now the problem is that the two do not render the same, moving the function to a different file adds, for some reason, an additional unprompted outer scrollbar

The images and small reproduction code is here : https://github.com/velvetysword/repro_nk

Am I missing something ?
Please help

Start with the linked velvety­sword/repro_nk reproduction and compare the v1 main.c setup with v2, including render_widget_list in gui.c and gui.h. Reproduce the two renderings and inspect the differences between the single-file and split-file versions; done means both render identically without the additional outer scrollbar.

Written by the indexing model from the issue text.