the position of window is changed when status change from show to hide,then to show

[kutear]

Describe the bug:

To Reproduce:

Steps to reproduce the behaviour:

1. create app with window
2. run app
3. drag app from position A to position B
4. hide window
5. show window
6. [ERROR] app will show at position A

Screenshots:

https://youtu.be/P_RNw4Idue0

Example code:

package main

import (
	"fyne.io/fyne"
	"fyne.io/fyne/app"
	"fyne.io/fyne/widget"
	"time"
)

func main() {
	a := app.New()

	w := a.NewWindow("Hello")
	w.SetContent(widget.NewVBox(
		widget.NewLabel("Hello Fyne!"),
		widget.NewButton("Hide", func() {
			w.Hide()
			time.AfterFunc(2*time.Second, func() { w.Show() })
		}),
	))

	w.Resize(fyne.NewSize(480, 320))
	w.ShowAndRun()
}

Device (please complete the following information):

GO111MODULE="on"
GOARCH="amd64"
GOBIN=""
GOCACHE="/home/XXX/.cache/go-build"
GOENV="/home/XXX/.config/go/env"
GOEXE=""
GOFLAGS=""
GOHOSTARCH="amd64"
GOHOSTOS="linux"
GOINSECURE=""
GONOPROXY=""
GONOSUMDB=""
GOOS="linux"
GOPATH="/home/XXX/Applications/Golang/Path"
GOPRIVATE=""
GOPROXY="https://goproxy.io,direct"
GOROOT="/home/XXX/Applications/Golang/Root"
GOSUMDB="sum.golang.org"
GOTMPDIR=""
GOTOOLDIR="/home/XXX/Applications/Golang/Root/pkg/tool/linux_amd64"
GCCGO="gccgo"
AR="ar"
CC="gcc"
CXX="g++"
CGO_ENABLED="1"
GOMOD="/dev/null"
CGO_CFLAGS="-g -O2"
CGO_CPPFLAGS=""
CGO_CXXFLAGS="-g -O2"
CGO_FFLAGS="-g -O2"
CGO_LDFLAGS="-g -O2"
PKG_CONFIG="pkg-config"
GOGCCFLAGS="-fPIC -m64 -pthread -fmessage-length=0 -fdebug-prefix-map=/tmp/go-build184922356=/tmp/go-build -gno-record-gcc-switches"

fyne version: a82c328
desktop: ubuntu18.04

[andydotxyz]

Oops, I forgot the pull request - this is now open

[andydotxyz]

On develop for testing