Close assignment window with main window

internal/gui/app.go

@@ -60,6 +60,8 @@ type App struct {
 	errorLabel       *widget.Label
 	reconnectButton  *widget.Button
 	assignmentButton *widget.Button
+
+	assignmentWindow fyne.Window
 }
 
 // NewApp creates the graphical rs2322tcp client application.
@@ -232,6 +234,12 @@ func (a *App) showAssignments() {
 		return
 	}
 
+	// Do not create another assignment window when one is already open.
+	if a.assignmentWindow != nil {
+		a.assignmentWindow.Show()
+		return
+	}
+
 	cfg := a.clientApplication.Config()
 	devices := a.clientApplication.Devices()
 
@@ -295,6 +303,19 @@ func (a *App) showAssignments() {
 		"Gerätezuordnung",
 	)
 	assignmentWindow.Resize(fyne.NewSize(650, 450))
+
+	// Remember the child window so it can be closed together with
+	// the main window.
+	a.assignmentWindow = assignmentWindow
+
+	assignmentWindow.SetOnClosed(func() {
+		// Only clear the reference if this is still the current
+		// assignment window.
+		if a.assignmentWindow == assignmentWindow {
+			a.assignmentWindow = nil
+		}
+	})
+
 	assignmentWindow.SetContent(
 		container.NewBorder(
 			nil,
@@ -309,18 +330,40 @@ func (a *App) showAssignments() {
 			container.NewVScroll(content),
 		),
 	)
+
 	assignmentWindow.Show()
 }
 
+// closeAssignmentWindow closes the currently open device-assignment window.
+//
+// This is deliberately kept separate from Close() so that the child window
+// can be closed without changing any configuration or technical client
+// state.
+func (a *App) closeAssignmentWindow() {
+	if a == nil {
+		return
+	}
+
+	if a.assignmentWindow == nil {
+		return
+	}
+
+	window := a.assignmentWindow
+	a.assignmentWindow = nil
+	window.Close()
+}
+
 // Close closes the technical client application.
 //
-// The Runtime and the server connection are closed before the GUI window
-// itself is closed.
+// Any open child GUI window is closed first. The technical client is then
+// shut down.
 func (a *App) Close() {
 	if a == nil {
 		return
 	}
 
+	a.closeAssignmentWindow()
+
 	_ = a.clientApplication.Close()
 }