I created this Dropdown menu in Unity 2017.3.1f1 using the standard "Dropdown":
Instead of the Template being the Dropdown's direct child there's a TemplatePanel that is the parent of both the Template and the ButtonsPanel (with a Horizontal Layout Group for the 3 buttons).
Inspector for Dropdown: click
As you can see, I changed the Template to TemplatePanel, so the buttons and the actual Template will be affected but when I start the game, it looks like this:
Changing it back to Template with the TemplatePanel always set to "active" (otherwise you wouldn't see anything because Template is still a child of the inactive TemplatePanel) makes it looks like this:
The positioning is fine but the buttons and the ButtonPanel are always there because they aren't affected by the script anymore. It looks like the Dropdown script is messing with the height but unfortunately I can't change it ("Unable to opem C:/..../UnityEngine.UI.dll").
Is it even possible to use a Dropdown like this and if so: What do I have to change to make it display everything properly?