WDropdown will not show menu if there are no other widgets

[uniformization]

Describe the bug

If you test the following code below, the dropdown will not open when clicked, the dropdown should open and show the values of the enum.

public class DropdownBugScreen extends WindowScreen {
    public enum ExampleEnum {
        Value1,
        Value2,
        Value3
    }

    public DropdownBugScreen() {
        super(GuiThemes.get(), "DropdownBugScreen");
    }

    @Override
    public void initWidgets() {
        WView view = add(theme.view()).expandX().widget();
        view.add(theme.dropdown(ExampleEnum.Value1));
    }
}

Steps to reproduce

To "fix" is, add this line to the end of the initWidgets function

view.add(theme.button("Select")).expandCellX();

If you use WHorizontalList, the dropdown will not open (even if you include the "fix" above)

Meteor Version

1.21.11-63

Minecraft Version

1.21.11

Operating System

Windows

Before submitting a bug report

• This bug wasn't already reported (I have searched bug reports on GitHub).

• This is a valid bug (I am able to reproduce this on the latest dev build).

[X-C-0]

This is probably related to this PR #6209.