Content not filling Dialog

[stuartmscott]

Describe the bug:

Content within a dialog is not expanded to fill the available space

Screenshots:

https://slack-files.com/T029RQSE6-F01CSCWNM4Y-8d46682e2c

Example code:

package main

import (
	"fmt"
	"fyne.io/fyne"
	"fyne.io/fyne/app"
	"fyne.io/fyne/dialog"
	"fyne.io/fyne/widget"
)

func main() {
	a := app.New()
	w := a.NewWindow("List Dialog")
	w.SetContent(widget.NewButton("Show List Dialog", func() {
		l := widget.NewList(
			func() int {
				return 10
			},
			func() fyne.CanvasObject {
				return widget.NewLabel("Template")
			},
			func(index int, item fyne.CanvasObject) {
				item.(*widget.Label).SetText(fmt.Sprintf("Item %d", index))
			})
		d := dialog.NewCustom("List Dialog", "OK", l, w)
		d.Show()
		d.Resize(fyne.NewSize(500, 500))
	}))
	w.Resize(fyne.NewSize(600, 600))
	w.ShowAndRun()
}

[okratitan]

Resolved by #1367