What exactly should happen if such an entry is clicked - if SmartGit is running and not running?

Build 16037 will contain this.

Sorry, I misunderstood you. I thought you don't want to see them in the Graph, but you want to hide them in the Branches view. Fortunately, there exists a solution for that. Please add following lines to the .git/config:

[smartgit "refLimit"]

    remoteBranchIncludeRegEx =

    remoteBranchExcludeRegEx =
    tagIncludeRegEx =
    tagExcludeRegEx = build-\\d{4}

and configure the values at the right.

Duplicate of https://smartgit.userecho.com/communities/1/topics/85-?

Already fixed since 19.1.

In SmartGit you can show/hide any ref you like - see the checkboxes in front of the refs in the Branches view.

If the worktree directory has already been deleted, use Repository | Prune Obsolete Worktrees from one of the other worktrees or the main repository.

SmartGit just reopens all the repositories (in one window) that were open before exiting, even if they were open in different windows. I reckon, you can't open multiple windows in SourceTree.

SmartGit should remember all the open repositories when closing it. I don't see how SourceTree would solve any of the problems you had.

If the target branch is the same as the head branch, you could use Push Up To.