add ability to logout of server (via new settings menu button)

ui/browsing/browsingpane.go

@@ -52,6 +52,8 @@ type BrowsingPane struct {
 	history    []SavedPage
 	historyIdx int
 
+	settingsBtn      *widget.Button
+	settingsMenu     *fyne.Menu
 	navBtnsContainer *fyne.Container
 	pageContainer    *fyne.Container
 	container        *fyne.Container
@@ -65,12 +67,21 @@ func NewBrowsingPane(app *backend.App) *BrowsingPane {
 	b.reload = widget.NewButtonWithIcon("", theme.ViewRefreshIcon(), b.Reload)
 	b.app.PlaybackManager.OnSongChange(b.onSongChange)
 	b.pageContainer = container.NewMax(
+		// TODO: get this color into the theme
 		canvas.NewRectangle(color.RGBA{R: 24, G: 24, B: 24, A: 255}),
 		layout.NewSpacer())
+	b.settingsBtn = widget.NewButtonWithIcon("", theme.SettingsIcon(), func() {
+		p := widget.NewPopUpMenu(b.settingsMenu,
+			fyne.CurrentApp().Driver().CanvasForObject(b.settingsBtn))
+		p.ShowAtPosition(fyne.NewPos(b.Size().Width-p.MinSize().Width-theme.Padding()/2,
+			b.navBtnsContainer.MinSize().Height+theme.Padding()))
+	})
+	b.settingsMenu = fyne.NewMenu("")
 	b.navBtnsContainer = container.NewHBox()
 	b.container = container.NewBorder(
 		container.New(layouts.NewLeftMiddleRightLayout(0),
-			container.NewHBox(b.back, b.forward, b.reload), b.navBtnsContainer, layout.NewSpacer()),
+			container.NewHBox(b.back, b.forward, b.reload), b.navBtnsContainer,
+			container.NewHBox(layout.NewSpacer(), b.settingsBtn)),
 		nil, nil, nil, b.pageContainer)
 	return b
 }
@@ -91,6 +102,11 @@ func (b *BrowsingPane) ClearHistory() {
 	b.historyIdx = 0
 }
 
+func (b *BrowsingPane) AddSettingsMenuItem(label string, action func()) {
+	b.settingsMenu.Items = append(b.settingsMenu.Items,
+		fyne.NewMenuItem(label, action))
+}
+
 func (b *BrowsingPane) AddNavigationButton(iconRes fyne.Resource, action func()) {
 	b.navBtnsContainer.Add(widget.NewButtonWithIcon("", iconRes, action))
 }