refactor(ui): extract MainForm status bar binding

MainStatusBar owns the status, location, selection and plate labels and
the click-vs-move location mode. Bind(EditNestForm)/Unbind() replace the
manual PlateView subscribe/unsubscribe pairs in OnMdiChildActivate;
MainForm keeps only its overlap-menu subscription. Applying the location
mode now detaches both mouse handlers first, which also drops the old
self-assignment of the mode flag.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

OpenNest/Forms/MainForm.File.cs

@@ -22,7 +22,7 @@ namespace OpenNest.Forms
             editForm.PlateChanged += (sender, e) =>
             {
                 NavigationEnableCheck();
-                UpdatePlateStatus();
+                statusBar.UpdatePlate();
                 mnuPlateRemove.Enabled = activeForm?.PlateManager.CanRemoveCurrent ?? false;
             };
             editForm.WindowState = windowState;

OpenNest/Forms/MainForm.Plate.cs

@@ -43,7 +43,7 @@ namespace OpenNest.Forms
             if (activeForm == null)
                 return;
             activeForm.ResizePlateToFitParts();
-            UpdatePlateStatus();
+            statusBar.UpdatePlate();
         }
 
         private void RotateCw_Click(object sender, EventArgs e)

OpenNest/Forms/MainForm.Status.cs

@@ -1,9 +1,5 @@
 using System;
-using System.Drawing;
-using System.Linq;
 using System.Windows.Forms;
-using OpenNest.Collections;
-using OpenNest.Geometry;
 
 namespace OpenNest.Forms
 {
@@ -58,159 +54,17 @@ namespace OpenNest.Forms
             NavigationEnableCheck(locked);
         }
 
-        private void UpdateLocationStatus()
-        {
-            if (activeForm == null)
-            {
-                locationStatusLabel.Text = string.Empty;
-                return;
-            }
-
-            locationStatusLabel.Text = string.Format(
-                "Location: [{0}, {1}]",
-                activeForm.PlateView.CurrentPoint.X.ToString("n4"),
-                activeForm.PlateView.CurrentPoint.Y.ToString("n4")
-            );
-        }
-
-        private void UpdatePlateStatus()
-        {
-            if (activeForm == null)
-            {
-                plateIndexStatusLabel.Text = string.Empty;
-                plateSizeStatusLabel.Text = string.Empty;
-                plateQtyStatusLabel.Text = string.Empty;
-                plateUtilStatusLabel.Text = string.Empty;
-                return;
-            }
-
-            plateIndexStatusLabel.Text = string.Format(
-                "Plate: {0} of {1}",
-                activeForm.PlateManager.CurrentIndex + 1,
-                activeForm.PlateManager.Count
-            );
-
-            plateSizeStatusLabel.Text = string.Format("Size: {0}", activeForm.PlateView.Plate.Size);
-
-            plateQtyStatusLabel.Text = string.Format(
-                "Qty: {0}",
-                activeForm.PlateView.Plate.Quantity
-            );
-
-            plateUtilStatusLabel.Text = string.Format(
-                "Util: {0:P1}",
-                activeForm.PlateView.Plate.Utilization()
-            );
-        }
-
-        private void UpdateSelectionStatus()
-        {
-            if (activeForm == null || activeForm.PlateView.SelectedParts.Count == 0)
-            {
-                selectionStatusLabel.Text = string.Empty;
-                return;
-            }
-
-            var selected = activeForm.PlateView.SelectedParts;
-
-            if (selected.Count == 1)
-            {
-                var box = selected[0].BoundingBox;
-                selectionStatusLabel.Text = string.Format(
-                    "Selected: [{0}, {1}] {2} x {3}",
-                    box.X.ToString("n4"),
-                    box.Y.ToString("n4"),
-                    box.Width.ToString("n4"),
-                    box.Length.ToString("n4")
-                );
-            }
-            else
-            {
-                var bounds = selected.Select(p => p.BasePart).ToList().GetBoundingBox();
-                selectionStatusLabel.Text = string.Format(
-                    "Selected ({0}): [{1}, {2}] {3} x {4}",
-                    selected.Count,
-                    bounds.X.ToString("n4"),
-                    bounds.Y.ToString("n4"),
-                    bounds.Width.ToString("n4"),
-                    bounds.Length.ToString("n4")
-                );
-            }
-        }
-
-        private void UpdateStatus()
-        {
-            UpdateLocationStatus();
-            UpdatePlateStatus();
-            UpdateSelectionStatus();
-        }
-
         private void EngineComboBox_SelectedIndexChanged(object sender, EventArgs e)
         {
             if (engineComboBox.SelectedItem is string name)
                 EngineSelection.EngineName = name;
         }
 
-        private void UpdateLocationMode()
-        {
-            if (activeForm == null)
-                return;
-
-            if (clickUpdateLocation)
-            {
-                clickUpdateLocation = true;
-                locationStatusLabel.ForeColor = Color.Gray;
-                activeForm.PlateView.MouseMove -= PlateView_MouseMove;
-                activeForm.PlateView.MouseClick += PlateView_MouseClick;
-            }
-            else
-            {
-                clickUpdateLocation = false;
-                locationStatusLabel.ForeColor = Color.Black;
-                activeForm.PlateView.MouseMove += PlateView_MouseMove;
-                activeForm.PlateView.MouseClick -= PlateView_MouseClick;
-            }
-        }
-
         #region Statusbar Events
 
-        private void LocationStatusLabel_Click(object sender, EventArgs e)
-        {
-            clickUpdateLocation = !clickUpdateLocation;
-            UpdateLocationMode();
-        }
+        private void LocationStatusLabel_Click(object sender, EventArgs e) =>
+            statusBar.ToggleLocationMode();
 
         #endregion Statusbar Events
-
-        #region PlateView Events
-
-        private void PlateView_PartAdded(object sender, ItemAddedEventArgs<Part> e) =>
-            UpdatePlateStatus();
-
-        private void PlateView_PartRemoved(object sender, ItemRemovedEventArgs<Part> e) =>
-            UpdatePlateStatus();
-
-        private void PlateView_MouseMove(object sender, MouseEventArgs e)
-        {
-            UpdateLocationStatus();
-        }
-
-        private void PlateView_MouseClick(object sender, MouseEventArgs e)
-        {
-            if (e.Button == MouseButtons.Left)
-                UpdateLocationStatus();
-        }
-
-        private void PlateView_StatusChanged(object sender, EventArgs e)
-        {
-            statusLabel1.Text = activeForm.PlateView.Status;
-        }
-
-        private void PlateView_SelectionChanged(object sender, EventArgs e)
-        {
-            UpdateSelectionStatus();
-        }
-
-        #endregion PlateView Events
     }
 }

OpenNest/Forms/MainForm.cs

@@ -17,7 +17,7 @@ namespace OpenNest.Forms
     {
         private EditNestForm activeForm;
 
-        private bool clickUpdateLocation;
+        private readonly MainStatusBar statusBar;
         private bool nestingInProgress;
         private CancellationTokenSource nestingCts;
         private readonly NestStorageController storage;
@@ -98,6 +98,8 @@ namespace OpenNest.Forms
             storage = new NestStorageController(this, text => statusLabel1.Text = text);
             storage.StateChanged += Storage_StateChanged;
             InitializeComponent();
+            statusBar = new MainStatusBar(statusLabel1, locationStatusLabel, selectionStatusLabel,
+                plateIndexStatusLabel, plateSizeStatusLabel, plateQtyStatusLabel, plateUtilStatusLabel);
             toolStrip1.Items.Add(CreateActionButton("btnCutPlanner", "Plan Cutting",
                 Resources.cut_planner, PlatePlanCutting_Click));
             toolStrip1.Items.Add(CreateActionButton("btnManualSequence", "Manual Sequence",
@@ -117,14 +119,12 @@ namespace OpenNest.Forms
             mnuViewZoomIn.ShortcutKeyDisplayString = "Ctrl+Plus";
             mnuViewZoomOut.ShortcutKeyDisplayString = "Ctrl+Minus";
 
-            clickUpdateLocation = true;
-
             this.SetBevel(false);
             AllowDrop = true;
 
             LoadPosts(PostProcessorLoader.Load(PostProcessorLoader.DefaultDirectory));
             EnableCheck();
-            UpdateStatus();
+            statusBar.UpdateAll();
 
             // Jobs-side plug-in discovery: INestingEngine implementations are registered per
             // assembly/type with per-DLL isolation. Existing plug-ins must implement the jobs
@@ -205,16 +205,9 @@ namespace OpenNest.Forms
                 editor.CuttingInspection.RequestClose();
             base.OnMdiChildActivate(e);
 
+            statusBar.Unbind();
             if (activeForm != null)
-            {
-                activeForm.PlateView.MouseMove -= PlateView_MouseMove;
-                activeForm.PlateView.MouseClick -= PlateView_MouseClick;
-                activeForm.PlateView.StatusChanged -= PlateView_StatusChanged;
                 activeForm.PlateView.OverlapStateChanged -= OverlapStateChanged;
-                activeForm.PlateView.SelectionChanged -= PlateView_SelectionChanged;
-                activeForm.PlateView.PartAdded -= PlateView_PartAdded;
-                activeForm.PlateView.PartRemoved -= PlateView_PartRemoved;
-            }
 
             // If nesting is in progress and the active form changed, cancel nesting
             if (nestingInProgress && nestingCts != null)
@@ -226,30 +219,18 @@ namespace OpenNest.Forms
             UpdateOverlapMenu();
 
             EnableCheck();
-            UpdatePlateStatus();
-            UpdateLocationStatus();
+            statusBar.Bind(activeForm);
 
             if (activeForm == null)
-            {
-                statusLabel1.Text = "";
-                selectionStatusLabel.Text = "";
                 return;
-            }
 
-            UpdateLocationMode();
-            UpdateSelectionStatus();
-            activeForm.PlateView.StatusChanged += PlateView_StatusChanged;
             activeForm.PlateView.OverlapStateChanged += OverlapStateChanged;
-            activeForm.PlateView.SelectionChanged += PlateView_SelectionChanged;
-            activeForm.PlateView.PartAdded += PlateView_PartAdded;
-            activeForm.PlateView.PartRemoved += PlateView_PartRemoved;
             var activeNest = activeForm.Nest;
             activeForm.PlateView.CanEditClamps = () => !ClampsInUse(activeNest);
             mnuViewDrawRapids.Checked = activeForm.PlateView.DrawRapid;
             mnuViewDrawPiercePoints.Checked = activeForm.PlateView.DrawPiercePoints;
             mnuViewDrawBounds.Checked = activeForm.PlateView.DrawBounds;
             mnuViewDrawCutDirection.Checked = activeForm.PlateView.DrawCutDirection;
-            statusLabel1.Text = activeForm.PlateView.Status;
         }
 
         protected override void OnLoad(EventArgs e)

OpenNest/Forms/MainStatusBar.cs

@@ -0,0 +1,214 @@
+using System;
+using System.Drawing;
+using System.Linq;
+using System.Windows.Forms;
+using OpenNest.Collections;
+using OpenNest.Geometry;
+
+namespace OpenNest.Forms
+{
+    /// <summary>
+    /// The main window's status labels for the active nest document: status text, cursor
+    /// location, selection bounds and plate index/size/quantity/utilization. The location
+    /// follows the mouse, or only left clicks while click mode is on (the default).
+    /// </summary>
+    internal sealed class MainStatusBar
+    {
+        private readonly ToolStripStatusLabel status;
+        private readonly ToolStripStatusLabel location;
+        private readonly ToolStripStatusLabel selection;
+        private readonly ToolStripStatusLabel plateIndex;
+        private readonly ToolStripStatusLabel plateSize;
+        private readonly ToolStripStatusLabel plateQty;
+        private readonly ToolStripStatusLabel plateUtil;
+
+        private EditNestForm form;
+        private bool clickUpdatesLocation = true;
+
+        public MainStatusBar(ToolStripStatusLabel status, ToolStripStatusLabel location,
+            ToolStripStatusLabel selection, ToolStripStatusLabel plateIndex, ToolStripStatusLabel plateSize,
+            ToolStripStatusLabel plateQty, ToolStripStatusLabel plateUtil)
+        {
+            this.status = status;
+            this.location = location;
+            this.selection = selection;
+            this.plateIndex = plateIndex;
+            this.plateSize = plateSize;
+            this.plateQty = plateQty;
+            this.plateUtil = plateUtil;
+        }
+
+        /// <summary>
+        /// Follows <paramref name="editForm"/>'s plate view after detaching from the previous
+        /// document; null clears every label.
+        /// </summary>
+        public void Bind(EditNestForm editForm)
+        {
+            Unbind();
+            form = editForm;
+            UpdatePlate();
+            UpdateLocation();
+
+            if (form == null)
+            {
+                status.Text = "";
+                selection.Text = "";
+                return;
+            }
+
+            ApplyLocationMode();
+            UpdateSelection();
+            var view = form.PlateView;
+            view.StatusChanged += PlateView_StatusChanged;
+            view.SelectionChanged += PlateView_SelectionChanged;
+            view.PartAdded += PlateView_PartAdded;
+            view.PartRemoved += PlateView_PartRemoved;
+            status.Text = view.Status;
+        }
+
+        public void Unbind()
+        {
+            if (form == null)
+                return;
+
+            var view = form.PlateView;
+            view.MouseMove -= PlateView_MouseMove;
+            view.MouseClick -= PlateView_MouseClick;
+            view.StatusChanged -= PlateView_StatusChanged;
+            view.SelectionChanged -= PlateView_SelectionChanged;
+            view.PartAdded -= PlateView_PartAdded;
+            view.PartRemoved -= PlateView_PartRemoved;
+            form = null;
+        }
+
+        public void ToggleLocationMode()
+        {
+            clickUpdatesLocation = !clickUpdatesLocation;
+            ApplyLocationMode();
+        }
+
+        public void UpdateAll()
+        {
+            UpdateLocation();
+            UpdatePlate();
+            UpdateSelection();
+        }
+
+        public void UpdateLocation()
+        {
+            if (form == null)
+            {
+                location.Text = string.Empty;
+                return;
+            }
+
+            location.Text = string.Format(
+                "Location: [{0}, {1}]",
+                form.PlateView.CurrentPoint.X.ToString("n4"),
+                form.PlateView.CurrentPoint.Y.ToString("n4")
+            );
+        }
+
+        public void UpdatePlate()
+        {
+            if (form == null)
+            {
+                plateIndex.Text = string.Empty;
+                plateSize.Text = string.Empty;
+                plateQty.Text = string.Empty;
+                plateUtil.Text = string.Empty;
+                return;
+            }
+
+            plateIndex.Text = string.Format(
+                "Plate: {0} of {1}",
+                form.PlateManager.CurrentIndex + 1,
+                form.PlateManager.Count
+            );
+
+            plateSize.Text = string.Format("Size: {0}", form.PlateView.Plate.Size);
+
+            plateQty.Text = string.Format(
+                "Qty: {0}",
+                form.PlateView.Plate.Quantity
+            );
+
+            plateUtil.Text = string.Format(
+                "Util: {0:P1}",
+                form.PlateView.Plate.Utilization()
+            );
+        }
+
+        public void UpdateSelection()
+        {
+            if (form == null || form.PlateView.SelectedParts.Count == 0)
+            {
+                selection.Text = string.Empty;
+                return;
+            }
+
+            var selected = form.PlateView.SelectedParts;
+
+            if (selected.Count == 1)
+            {
+                var box = selected[0].BoundingBox;
+                selection.Text = string.Format(
+                    "Selected: [{0}, {1}] {2} x {3}",
+                    box.X.ToString("n4"),
+                    box.Y.ToString("n4"),
+                    box.Width.ToString("n4"),
+                    box.Length.ToString("n4")
+                );
+            }
+            else
+            {
+                var bounds = selected.Select(p => p.BasePart).ToList().GetBoundingBox();
+                selection.Text = string.Format(
+                    "Selected ({0}): [{1}, {2}] {3} x {4}",
+                    selected.Count,
+                    bounds.X.ToString("n4"),
+                    bounds.Y.ToString("n4"),
+                    bounds.Width.ToString("n4"),
+                    bounds.Length.ToString("n4")
+                );
+            }
+        }
+
+        private void ApplyLocationMode()
+        {
+            if (form == null)
+                return;
+
+            var view = form.PlateView;
+            // Detach both first so repeated calls never stack handlers.
+            view.MouseMove -= PlateView_MouseMove;
+            view.MouseClick -= PlateView_MouseClick;
+            if (clickUpdatesLocation)
+            {
+                location.ForeColor = Color.Gray;
+                view.MouseClick += PlateView_MouseClick;
+            }
+            else
+            {
+                location.ForeColor = Color.Black;
+                view.MouseMove += PlateView_MouseMove;
+            }
+        }
+
+        private void PlateView_PartAdded(object sender, ItemAddedEventArgs<Part> e) => UpdatePlate();
+
+        private void PlateView_PartRemoved(object sender, ItemRemovedEventArgs<Part> e) => UpdatePlate();
+
+        private void PlateView_MouseMove(object sender, MouseEventArgs e) => UpdateLocation();
+
+        private void PlateView_MouseClick(object sender, MouseEventArgs e)
+        {
+            if (e.Button == MouseButtons.Left)
+                UpdateLocation();
+        }
+
+        private void PlateView_StatusChanged(object sender, EventArgs e) => status.Text = form.PlateView.Status;
+
+        private void PlateView_SelectionChanged(object sender, EventArgs e) => UpdateSelection();
+    }
+}