[Bug]: Tree arrows in the Library window show inconsistently for folders without child folders.

[kwvanderlinde]

Describe the Bug

If a Library folder has no child folders, it at first has an expansion arrow suggesting there is more to be revealed by clicking it. But when I click the arrow, nothing happens and the arrow disappears, making it feel like the tree has broken.

To Reproduce

1. Expand a folder in the Library window until you get to a known folder with no child folders. Notice the arrow to the left.
2. Click the arrow.
3. Notice the arrow disappear with no other change to the display.

Expected Behaviour

Preferred: the arrow should not display if there are no child folders to reveal.

Alternative: the arrow should always display, even after expanding, regardless of whether there are child folders. This will make it clear that something is happening as the arrow will transition from one state to the other.

Screenshots

Here is an example set of root folders: Some of them have child folders, but it's not possible to tell which ones.

After expanding & collapsing each one, the absence of arrows makes it clear which ones have nothing further to show:

I'm suggesting the latter should be the way the tree always looks.

MapTool Info

1.14.1

Desktop

Linux Mint 21.2

Additional Context

No response