ILayoutElement.flexibleWidth

설명

The extra relative width this layout element should be allocated if there is additional available space.

using UnityEngine;
using System.Collections;
using UnityEngine.UI; // Required when using UI elements.

public class ExampleClass : MonoBehaviour
{
	public Transform MyContentPanel;

	//Sets the flexible height on on all children in the content panel.
	public void Start()
	{
		//Assign all the children of the content panel to an array.
		LayoutElement[] myLayoutElements = MyContentPanel.GetComponentsInChildren<LayoutElement> ();

		//For each child in the array change its LayoutElement's flexible width to 200.
		foreach(LayoutElement element in myLayoutElements)
		{
			element.flexibleWidth = 200f;
		}
	}
}

Setting preferredWidth to -1 removed the preferredWidth.