func buildRadioButtonDemo(event gwu.Event) gwu.Comp {
	p := gwu.NewPanel()

	p.Add(gwu.NewLabel("Select your favorite programming language:"))

	group := gwu.NewRadioGroup("lang")
	rbs := []gwu.RadioButton{gwu.NewRadioButton("Go", group), gwu.NewRadioButton("Java", group), gwu.NewRadioButton("C / C++", group),
		gwu.NewRadioButton("Python", group), gwu.NewRadioButton("QBasic (nah this can't be your favorite)", group)}
	rbs[4].SetEnabled(false)

	for _, rb := range rbs {
		p.Add(rb)
	}

	p.AddVSpace(20)
	p.Add(gwu.NewLabel("Select your favorite computer game:"))

	group = gwu.NewRadioGroup("game")
	rbs = []gwu.RadioButton{gwu.NewRadioButton("StarCraft II", group), gwu.NewRadioButton("Minecraft", group),
		gwu.NewRadioButton("Other", group)}

	for _, rb := range rbs {
		p.Add(rb)
	}

	return p
}

func buildSwitchButtonDemo(event gwu.Event) gwu.Comp {
	p := gwu.NewPanel()
	p.SetCellPadding(1)

	row := gwu.NewHorizontalPanel()
	row.Add(gwu.NewLabel("Here's an ON/OFF switch which enables/disables the other one:"))
	sw := gwu.NewSwitchButton()
	sw.SetOnOff("ENB", "DISB")
	sw.SetState(true)
	row.Add(sw)
	p.Add(row)

	p.AddVSpace(10)
	row = gwu.NewHorizontalPanel()
	row.Add(gwu.NewLabel("And the other one:"))
	sw2 := gwu.NewSwitchButton()
	sw2.SetEnabled(true)
	sw2.Style().SetWidthPx(100)
	row.Add(sw2)
	sw.AddEHandlerFunc(func(e gwu.Event) {
		sw2.SetEnabled(sw.State())
		e.MarkDirty(sw2)
	}, gwu.ETYPE_CLICK)
	p.Add(row)

	return p
}

func buildLabelDemo(event gwu.Event) gwu.Comp {
	p := gwu.NewPanel()

	p.Add(gwu.NewLabel("This is a Label."))
	p.Add(gwu.NewLabel("世界 And another one. ㅈㅈ"))
	p.Add(gwu.NewLabel("Nothing special about them, but they may be the mostly used components."))

	p.AddVSpace(20)
	p.Add(gwu.NewLabel("You can change their text:"))
	b := gwu.NewButton("Change!")
	b.AddEHandlerFunc(func(e gwu.Event) {
		for i := 0; i < p.CompsCount(); i++ {
			if l, ok := p.CompAt(i).(gwu.Label); ok && l != b {
				reversed := []rune(l.Text())
				for i, j := 0, len(reversed)-1; i < j; i, j = i+1, j-1 {
					reversed[i], reversed[j] = reversed[j], reversed[i]
				}
				l.SetText(string(reversed))
			}
		}
		e.MarkDirty(p)
	}, gwu.ETYPE_CLICK)
	p.Add(b)

	return p
}

func main() {
	// Create GUI server
	//server := gwu.NewServer("guitest", "")
	server := gwu.NewServerTLS("guitest", "", "test_tls/cert.pem", "test_tls/key.pem")
	server.SetText("Test GUI Application")

	server.AddSessCreatorName("login", "Login Window")
	server.AddSHandler(SessHandler{})

	win := gwu.NewWindow("home", "Home Window")
	l := gwu.NewLabel("Home, sweet home of " + server.Text())
	l.Style().SetFontWeight(gwu.FONT_WEIGHT_BOLD).SetFontSize("130%")
	win.Add(l)
	win.Add(gwu.NewLabel("Click on the button to login:"))
	b := gwu.NewButton("Login")
	b.AddEHandlerFunc(func(e gwu.Event) {
		e.ReloadWin("login")
	}, gwu.ETYPE_CLICK)
	win.Add(b)

	server.AddWin(win)

	server.SetLogger(log.New(os.Stdout, "", log.LstdFlags))

	// Start GUI server
	if err := server.Start(); err != nil {
		fmt.Println("Error: Cound not start GUI server:", err)
		return
	}
}

func buildCheckBoxDemo(event gwu.Event) gwu.Comp {
	p := gwu.NewPanel()

	suml := gwu.NewLabel("")

	p.Add(gwu.NewLabel("Check the days you want to work on:"))

	cbs := []gwu.CheckBox{gwu.NewCheckBox("Monday"), gwu.NewCheckBox("Tuesday"), gwu.NewCheckBox("Wednesday"),
		gwu.NewCheckBox("Thursday"), gwu.NewCheckBox("Friday"), gwu.NewCheckBox("Saturday"), gwu.NewCheckBox("Sunday")}
	cbs[5].SetEnabled(false)
	cbs[6].SetEnabled(false)

	for _, cb := range cbs {
		p.Add(cb)
		cb.AddEHandlerFunc(func(e gwu.Event) {
			sum := 0
			for _, cb2 := range cbs {
				if cb2.State() {
					sum++
				}
			}
			suml.SetText(fmt.Sprintf("%d day%s is a total of %d hours a week.", sum, plural(sum), sum*8))
			e.MarkDirty(suml)
		}, gwu.ETYPE_CLICK)
	}

	p.Add(suml)

	return p
}

func buildPanelDemo(event gwu.Event) gwu.Comp {
	p := gwu.NewPanel()

	p.Add(gwu.NewLabel("Panel with horizontal layout:"))
	h := gwu.NewHorizontalPanel()
	for i := 1; i <= 5; i++ {
		h.Add(gwu.NewButton("Button " + strconv.Itoa(i)))
	}
	p.Add(h)

	p.AddVSpace(20)
	p.Add(gwu.NewLabel("Panel with vertical layout:"))
	v := gwu.NewVerticalPanel()
	for i := 1; i <= 5; i++ {
		v.Add(gwu.NewButton("Button " + strconv.Itoa(i)))
	}
	p.Add(v)

	p.AddVSpace(20)
	p.Add(gwu.NewLabel("Panel with natural layout:"))
	n := gwu.NewNaturalPanel()
	for i := 1; i <= 20; i++ {
		n.Add(gwu.NewButton("LONG BUTTON " + strconv.Itoa(i)))
	}
	p.Add(n)

	return p
}

func buildHomeDemo(event gwu.Event) gwu.Comp {
	p := gwu.NewPanel()

	p.Add(gwu.NewLabel("This app is written in and showcases Gowut version " + gwu.GOWUT_VERSION + "."))
	p.AddVSpace(20)
	p.Add(gwu.NewLabel("Select components on the left side to see them in action."))

	return p
}

func buildWindowDemo(event gwu.Event) gwu.Comp {
	p := gwu.NewPanel()

	p.Add(gwu.NewLabel("The Window represents the whole window, the page inside the browser."))
	p.AddVSpace(5)
	p.Add(gwu.NewLabel("The Window is the top of the component hierarchy. It is an extension of the Panel."))

	return p
}

func buildImageDemo(event gwu.Event) gwu.Comp {
	p := gwu.NewPanel()

	p.Add(gwu.NewLabel("Google's logo:"))
	img := gwu.NewImage("Google's logo", "https://www.google.com/images/srpr/logo3w.png")
	img.Style().SetSizePx(275, 95)
	p.Add(img)

	p.AddVSpace(20)
	p.Add(gwu.NewLabel("Go's Gopher:"))
	img = gwu.NewImage("Go's Gopher", "http://golang.org/doc/gopher/frontpage.png")
	img.Style().SetSizePx(250, 340)
	p.Add(img)

	return p
}

func makeExpander(dir string) gwu.Expander {
	e := gwu.NewExpander()
	e.SetHeader(gwu.NewLabel(dir))
	e.Style().SetPaddingLeft("20")
	expanderDir[e] = dir
	return e
}

func buildButtonDemo(event gwu.Event) gwu.Comp {
	p := gwu.NewPanel()

	l := gwu.NewLabel("")

	btnp := gwu.NewHorizontalPanel()
	b := gwu.NewButton("Normal Button")
	b.AddEHandlerFunc(func(e gwu.Event) {
		switch e.Type() {
		case gwu.ETYPE_MOUSE_OVER:
			l.SetText("Mouse is over...")
		case gwu.ETYPE_MOUSE_OUT:
			l.SetText("Mouse is out.")
		case gwu.ETYPE_CLICK:
			x, y := e.Mouse()
			l.SetText(fmt.Sprintf("Clicked at x=%d, y=%d", x, y))
		}
		e.MarkDirty(l)
	}, gwu.ETYPE_CLICK, gwu.ETYPE_MOUSE_OVER, gwu.ETYPE_MOUSE_OUT)
	btnp.Add(b)

	b = gwu.NewButton("Disabled Button")
	b.SetEnabled(false)
	btnp.Add(b)

	p.Add(btnp)

	p.Add(l)

	return p
}

func buildPasswBoxDemo(event gwu.Event) gwu.Comp {
	p := gwu.NewPanel()

	p.Add(gwu.NewLabel("Enter your password:"))
	p.Add(gwu.NewPasswBox(""))

	return p
}

func buildLinkDemo(event gwu.Event) gwu.Comp {
	p := gwu.NewPanel()
	p.SetCellPadding(3)

	p.Add(gwu.NewLink("Visit Gowut Home page", "https://sites.google.com/site/gowebuitoolkit/"))
	p.Add(gwu.NewLink("Visit Gowut Project page", "https://github.com/icza/gowut"))

	row := gwu.NewHorizontalPanel()
	row.SetCellPadding(3)
	row.Add(gwu.NewLabel("Discussion forum:"))
	row.Add(gwu.NewLink("https://groups.google.com/d/forum/gowebuitoolkit", "https://groups.google.com/d/forum/gowebuitoolkit"))
	p.Add(row)

	row = gwu.NewHorizontalPanel()
	row.SetCellPadding(3)
	row.Add(gwu.NewLabel("Send e-mail to the Gowut author:"))
	email := "iczaaa" + "@" + "gmail.com"
	row.Add(gwu.NewLink("András Belicza <"+email+">", "mailto:"+email))
	p.Add(row)

	return p
}

func buildLinkContainerDemo(event gwu.Event) gwu.Comp {
	p := gwu.NewPanel()

	link := gwu.NewLink("An obvious link, to Google Home", "https://google.com/")
	inside := gwu.NewPanel()
	inside.Style().SetBorder2(1, gwu.BRD_STYLE_SOLID, gwu.CLR_GRAY)
	inside.Add(gwu.NewLabel("Everything inside this box also links to Google!"))
	inside.Add(gwu.NewButton("Me too!"))
	link.SetComp(inside)
	p.Add(link)

	return p
}

func buildTextBoxDemo(event gwu.Event) gwu.Comp {
	p := gwu.NewPanel()

	p.Add(gwu.NewLabel("Enter your name (max 15 characters):"))
	row := gwu.NewHorizontalPanel()
	tb := gwu.NewTextBox("")
	tb.SetMaxLength(15)
	tb.AddSyncOnETypes(gwu.ETYPE_KEY_UP)
	length := gwu.NewLabel("")
	length.Style().SetFontSize("80%").SetFontStyle(gwu.FONT_STYLE_ITALIC)
	tb.AddEHandlerFunc(func(e gwu.Event) {
		rem := 15 - len(tb.Text())
		length.SetText(fmt.Sprintf("(%d character%s left...)", rem, plural(rem)))
		e.MarkDirty(length)
	}, gwu.ETYPE_CHANGE, gwu.ETYPE_KEY_UP)
	row.Add(tb)
	row.Add(length)
	p.Add(row)

	p.AddVSpace(10)
	p.Add(gwu.NewLabel("Short biography:"))
	bio := gwu.NewTextBox("")
	bio.SetRows(5)
	bio.SetCols(40)
	p.Add(bio)

	p.AddVSpace(10)
	rtb := gwu.NewTextBox("This is just a read-only text box...")
	rtb.SetReadOnly(true)
	p.Add(rtb)

	p.AddVSpace(10)
	dtb := gwu.NewTextBox("...and a disabled one.")
	dtb.SetEnabled(false)
	p.Add(dtb)

	return p
}

func buildListBoxDemo(event gwu.Event) gwu.Comp {
	p := gwu.NewPanel()

	row := gwu.NewHorizontalPanel()
	l := gwu.NewLabel("Select a background color:")
	row.Add(l)
	lb := gwu.NewListBox([]string{"", "Black", "Red", "Green", "Blue", "White"})
	lb.AddEHandlerFunc(func(e gwu.Event) {
		l.Style().SetBackground(lb.SelectedValue())
		e.MarkDirty(l)
	}, gwu.ETYPE_CHANGE)
	row.Add(lb)
	p.Add(row)

	p.AddVSpace(10)
	p.Add(gwu.NewLabel("Select numbers that add up to 89:"))
	sumLabel := gwu.NewLabel("")
	lb2 := gwu.NewListBox([]string{"1", "2", "4", "8", "16", "32", "64", "128"})
	lb2.SetMulti(true)
	lb2.SetRows(10)
	lb2.AddEHandlerFunc(func(e gwu.Event) {
		sum := 0
		for _, idx := range lb2.SelectedIndices() {
			sum += 1 << uint(idx)
		}
		if sum == 89 {
			sumLabel.SetText("Hooray! You did it!")
		} else {
			sumLabel.SetText(fmt.Sprintf("Now quite there... (sum = %d)", sum))
		}
		e.MarkDirty(sumLabel)
	}, gwu.ETYPE_CHANGE)
	p.Add(lb2)
	p.Add(sumLabel)

	return p
}

func buildExpanderDemo(event gwu.Event) gwu.Comp {
	p := gwu.NewPanel()

	l := gwu.NewLabel("Click on the Expander's header.")
	l.Style().SetColor(gwu.CLR_GREEN)
	p.Add(l)
	p.AddVSpace(5)
	e := gwu.NewExpander()
	e.SetHeader(gwu.NewLabel("I'm an Expander."))
	e.SetContent(gwu.NewLabel("I'm the content of the Expander."))
	p.Add(e)
	e.AddEHandlerFunc(func(ev gwu.Event) {
		if e.Expanded() {
			l.SetText("You expanded it.")
		} else {
			l.SetText("You collapsed it.")
		}
		ev.MarkDirty(l)
	}, gwu.ETYPE_STATE_CHANGE)

	p.AddVSpace(20)
	var ee gwu.Expander
	for i := 4; i >= 0; i-- {
		e2 := gwu.NewExpander()
		e2.SetHeader(gwu.NewLabel("I hide embedded expanders. #" + strconv.Itoa(i)))
		if i == 4 {
			e2.SetContent(gwu.NewLabel("No more."))
		} else {
			e2.SetContent(ee)
		}
		ee = e2
	}
	p.Add(ee)

	return p
}

func buildTableDemo(event gwu.Event) gwu.Comp {
	p := gwu.NewPanel()

	l := gwu.NewLabel("Tip: Switch to the 'debug' theme (top right) to see cell borders.")
	l.Style().SetColor(gwu.CLR_RED).SetFontStyle(gwu.FONT_STYLE_ITALIC)
	p.Add(l)

	p.AddVSpace(20)
	p.Add(gwu.NewLabel("A simple form aligned with a table:"))
	p.AddVSpace(10)
	t := gwu.NewTable()
	t.SetCellPadding(2)
	t.EnsureSize(2, 2)
	var c gwu.Comp
	t.Add(gwu.NewLabel("User name:"), 0, 0)
	c = gwu.NewTextBox("")
	c.Style().SetWidthPx(160)
	t.Add(c, 0, 1)
	t.Add(gwu.NewLabel("Password:"), 1, 0)
	c = gwu.NewPasswBox("")
	c.Style().SetWidthPx(160)
	t.Add(c, 1, 1)
	t.Add(gwu.NewLabel("Go to:"), 2, 0)
	c = gwu.NewListBox([]string{"Inbox", "User preferences", "Last visited page"})
	c.Style().SetWidthPx(160)
	t.Add(c, 2, 1)
	p.Add(t)

	p.AddVSpace(30)
	p.Add(gwu.NewLabel("Advanced table structure with modified alignment, row and col spans:"))
	p.AddVSpace(10)
	t = gwu.NewTable()
	t.Style().SetBorder2(1, gwu.BRD_STYLE_SOLID, gwu.CLR_GREY)
	t.SetAlign(gwu.HA_RIGHT, gwu.VA_TOP)
	t.EnsureSize(5, 5)
	for row := 0; row < 5; row++ {
		for col := 0; col < 5; col++ {
			t.Add(gwu.NewButton("Button "+strconv.Itoa(row)+strconv.Itoa(col)), row, col)
		}
	}
	t.SetColSpan(2, 1, 2)
	t.SetRowSpan(3, 1, 2)
	t.CellFmt(2, 2).Style().SetSizePx(150, 80)
	t.CellFmt(2, 2).SetAlign(gwu.HA_RIGHT, gwu.VA_BOTTOM)
	t.RowFmt(2).SetAlign(gwu.HA_DEFAULT, gwu.VA_MIDDLE)
	t.CompAt(2, 1).Style().SetFullSize()
	t.CompAt(4, 2).Style().SetFullWidth()
	t.RowFmt(0).Style().SetBackground(gwu.CLR_RED)
	t.RowFmt(1).Style().SetBackground(gwu.CLR_GREEN)
	t.RowFmt(2).Style().SetBackground(gwu.CLR_BLUE)
	t.RowFmt(3).Style().SetBackground(gwu.CLR_GREY)
	t.RowFmt(4).Style().SetBackground(gwu.CLR_TEAL)
	p.Add(t)

	return p
}

func buildHtmlDemo(event gwu.Event) gwu.Comp {
	p := gwu.NewPanel()

	html := `<span onclick="alert('Hi from Html!');">Hi! I'm inserted as HTML. Click on me!</span>`

	p.Add(gwu.NewLabel("The following HTML code is inserted after the text box as an Html component:"))
	ta := gwu.NewTextBox(html)
	ta.SetReadOnly(true)
	ta.Style().SetWidthPx(500)
	ta.SetRows(4)
	p.Add(ta)

	p.AddVSpace(20)
	h := gwu.NewHtml(html)
	p.Add(h)

	return p
}

func main() {
	expanderDir = make(map[gwu.Expander]string)
	// Create and build a window
	win := gwu.NewWindow("main", "goperu - peruse files with browser")
	win.Style().SetFullWidth()
	win.SetHAlign(gwu.HA_LEFT)
	win.SetCellPadding(2)

	//win.SetTheme(gwu.THEME_DEBUG)

	p := gwu.NewPanel()
	p.Style().SetFullWidth()
	hostname, err := os.Hostname()
	if err != nil {
		hostname = ""
	}

	link := gwu.NewLink("goperu", "https://github.com/gnewton/goperu")
	p.Add(link)
	p.AddVSpace(10)

	l := gwu.NewLabel(hostname + ": Explore")
	l.Style().SetColor(gwu.CLR_GREEN)
	p.Add(l)

	p.AddVSpace(20)

	e := makeExpander(baseDir)

	expanderDir[e] = baseDir

	p.Add(e)
	e.AddEHandler(handler, gwu.ETYPE_STATE_CHANGE)
	//e.AddEHandler(handler, gwu.ETYPE_MOUSE_DOWN)
	win.Add(p)

	// Create and start a GUI server (omitting error check)
	server := gwu.NewServer("goperu", "localhost:8081")
	server.SetText("goperu")
	server.AddWin(win)
	server.Start("") // Also opens windows list in browser
}