Understanding expandable icons in branch view

[miwal]

I have two parallel branches, one went ahead of the other, then I merged the one that was ahead back into the one that was behind. This was a merge commit.

I notice the pink square which indicates a commit, in the case of the merge commit, is now a hollow pink square (no fill color), and it can be clicked, to expand the branch which was merged into it.

I’d just like to completely nail my understanding of what this means.

Is the merged branch hidden because the branch I am now looking at is fully up to date with it? What are the cases when merge will hide a branch and allow a click to reveal more information - is this the only case?

[bschaaf]

Sublime Merge allows any merge commit too be collapsed. All of them are collapsed by default (This can be changed in the settings). Which commits collapsing a merge commit hides is purely determined on the order of parents in the merge commit, the first parent of the merge commit it taken as the “base” and stays visible while the rest are hidden.