Phase 7: region box editor in the wallpaper maker

"Edit cell boxes" mode: the selected cell grows resize handles on the
preview -- drag to move/resize with live outline tracking and a re-render
on drop, or type exact X/Y/W/H in the new geometry fields. Plain clicks
still select and cycle stacked cells (click-vs-drag resolved by a movement
threshold on mouse-up). The move/resize math is pure and unit-tested
(OverlayRegionEdit: corner/edge/move handle hit-testing with tolerance,
min-size clamped resizing that pins the opposite edge). "Save template"
persists the shared cell geometry back to the regions.json; "Reload
template" re-reads it to discard unsaved box edits. Cursor feedback per
handle; template save/reload disabled when no template path was supplied.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

docs/PLAN.md

@@ -239,11 +239,16 @@ Replaces the legacy Google-Sheet → `.data` → GIMP → Script-Fu pipeline
   exercised end-to-end on the real cockpit art (`regions.json` + `riojoy.png` +
   `TEST.data`) by `OverlayRenderIntegrationTests`. `RioJoy.Tray/WallpaperApplier`
   applies the result via `SystemParametersInfo`.
-- **Region authoring — extraction done ✅.** `tools/XcfRegionExtract` parses the
+- **Region authoring — done ✅.** `tools/XcfRegionExtract` parses the
   GIMP source (`riojoy.xcf`) and writes the 119-cell
   `docs/reference/customBackground/regions.json` (per-layer offsets/size/font/color,
   `BaseImagePath` → exported `riojoy.png`), anchored by `CockpitRegionsTests`.
-  ⏳ Still to do: an in-app box editor for tweaks.
+  The **in-app box editor** lives in the wallpaper maker ("Edit cell boxes"): the
+  selected cell grows resize handles — drag to move/resize (plain clicks still
+  cycle stacked cells), or type exact X/Y/W/H — with the move/resize math in
+  `RioJoy.Core/Overlay/OverlayRegionEdit` (unit-tested, min-size clamped).
+  "Save template" persists the shared geometry back to the regions.json;
+  "Reload template" discards unsaved box edits.
 - **Runtime wiring — done ✅ (opt-in).** `RioJoy.Overlay/ProfileWallpaperGenerator`
   renders a profile's labels onto the template base image; `RioCoordinator`
   generates + applies the wallpaper on profile activation when

src/RioJoy.Core/Overlay/OverlayRegionEdit.cs

@@ -0,0 +1,97 @@
+namespace RioJoy.Core.Overlay;
+
+/// <summary>Which part of a region's box a drag grabs.</summary>
+public enum OverlayBoxHandle
+{
+    None,
+    Move,
+    North, South, East, West,
+    NorthWest, NorthEast, SouthWest, SouthEast,
+}
+
+/// <summary>
+/// The pure math behind the wallpaper maker's box editor: which handle a
+/// template-space point grabs on a region, and the region's new rectangle after
+/// dragging that handle. Kept UI-free so it is unit-testable; the canvas only
+/// converts mouse pixels to template space and applies the result.
+/// </summary>
+public static class OverlayRegionEdit
+{
+    /// <summary>
+    /// The handle at a template-space point: corners win over edges, edges over
+    /// <see cref="OverlayBoxHandle.Move"/> (anywhere else inside the box), all
+    /// within <paramref name="tolerance"/> template pixels of the border.
+    /// </summary>
+    public static OverlayBoxHandle HitHandle(OverlayRegion region, double x, double y, double tolerance)
+    {
+        if (region is null) throw new ArgumentNullException(nameof(region));
+
+        double l = region.X, t = region.Y, r = region.X + region.Width, b = region.Y + region.Height;
+        if (x < l - tolerance || x > r + tolerance || y < t - tolerance || y > b + tolerance)
+            return OverlayBoxHandle.None;
+
+        bool west = Math.Abs(x - l) <= tolerance;
+        bool east = Math.Abs(x - r) <= tolerance;
+        bool north = Math.Abs(y - t) <= tolerance;
+        bool south = Math.Abs(y - b) <= tolerance;
+
+        if (north && west) return OverlayBoxHandle.NorthWest;
+        if (north && east) return OverlayBoxHandle.NorthEast;
+        if (south && west) return OverlayBoxHandle.SouthWest;
+        if (south && east) return OverlayBoxHandle.SouthEast;
+        if (north) return OverlayBoxHandle.North;
+        if (south) return OverlayBoxHandle.South;
+        if (west) return OverlayBoxHandle.West;
+        if (east) return OverlayBoxHandle.East;
+
+        return x >= l && x < r && y >= t && y < b ? OverlayBoxHandle.Move : OverlayBoxHandle.None;
+    }
+
+    /// <summary>
+    /// The rectangle after dragging <paramref name="handle"/> by (dx, dy) template
+    /// pixels from the drag-start rectangle. Resizes clamp so width/height never
+    /// drop below <paramref name="minSize"/> (the opposite edge stays put).
+    /// </summary>
+    public static (double X, double Y, double Width, double Height) Apply(
+        double x, double y, double width, double height,
+        OverlayBoxHandle handle, double dx, double dy, double minSize = 4)
+    {
+        double l = x, t = y, r = x + width, b = y + height;
+
+        switch (handle)
+        {
+            case OverlayBoxHandle.Move:
+                return (x + dx, y + dy, width, height);
+            case OverlayBoxHandle.West:
+            case OverlayBoxHandle.NorthWest:
+            case OverlayBoxHandle.SouthWest:
+                l = Math.Min(l + dx, r - minSize);
+                break;
+        }
+
+        switch (handle)
+        {
+            case OverlayBoxHandle.East:
+            case OverlayBoxHandle.NorthEast:
+            case OverlayBoxHandle.SouthEast:
+                r = Math.Max(r + dx, l + minSize);
+                break;
+        }
+
+        switch (handle)
+        {
+            case OverlayBoxHandle.North:
+            case OverlayBoxHandle.NorthWest:
+            case OverlayBoxHandle.NorthEast:
+                t = Math.Min(t + dy, b - minSize);
+                break;
+            case OverlayBoxHandle.South:
+            case OverlayBoxHandle.SouthWest:
+            case OverlayBoxHandle.SouthEast:
+                b = Math.Max(b + dy, t + minSize);
+                break;
+        }
+
+        return (l, t, r - l, b - t);
+    }
+}

src/RioJoy.Tray/Editor/WallpaperCanvas.cs

@@ -13,11 +13,25 @@ namespace RioJoy.Tray.Editor;
 /// </summary>
 internal sealed class WallpaperCanvas : Control
 {
+    // Grabbing a handle within this many control pixels counts as a hit; a press
+    // that moves less than the drag threshold is treated as a click (cell cycling).
+    private const float HandleGrabPx = 5f;
+    private const int DragThresholdPx = 3;
+
     private Bitmap? _image;
     private string? _selectedRegionName;
     private bool _showOutlines = true;
+    private bool _editMode;
     private OverlayRegion? _hover;
 
+    // In-flight box drag: the grabbed handle, the mouse-down point (control px),
+    // the region's rectangle at mouse-down (template px), and whether the press
+    // has moved far enough to count as a drag rather than a click.
+    private OverlayBoxHandle _dragHandle = OverlayBoxHandle.None;
+    private Point _downControl;
+    private (double X, double Y, double W, double H) _downRect;
+    private bool _dragging;
+
     public WallpaperCanvas()
     {
         DoubleBuffered = true;
@@ -42,12 +56,33 @@ internal sealed class WallpaperCanvas : Control
         set { _showOutlines = value; Invalidate(); }
     }
 
+    /// <summary>
+    /// Box-editing mode: the selected cell grows resize handles and can be dragged;
+    /// clicks (without a drag) still select/cycle cells as usual.
+    /// </summary>
+    public bool EditMode
+    {
+        get => _editMode;
+        set
+        {
+            _editMode = value;
+            if (!value) Cursor = Cursors.Default;
+            Invalidate();
+        }
+    }
+
     /// <summary>Raised with template-space coordinates when the wallpaper is clicked.</summary>
     public event Action<double, double>? TemplateClicked;
 
     /// <summary>Raised when the topmost cell under the mouse changes (null = none).</summary>
     public event Action<OverlayRegion?>? HoverChanged;
 
+    /// <summary>Raised while a box drag mutates the selected region's geometry.</summary>
+    public event Action? SelectedGeometryChanged;
+
+    /// <summary>Raised when a box drag ends (time to re-render the labels).</summary>
+    public event Action? GeometryCommitted;
+
     /// <summary>Swap in a freshly rendered wallpaper; the canvas owns (and disposes) it.</summary>
     public void SetImage(Bitmap? image)
     {
@@ -92,13 +127,50 @@ internal sealed class WallpaperCanvas : Control
             using var pen = new Pen(Color.Gold, 2f);
             RectangleF rc = ToControl(selected, fit);
             g.DrawRectangle(pen, rc.X, rc.Y, rc.Width, rc.Height);
+
+            if (_editMode)
+            {
+                using var fill = new SolidBrush(Color.Gold);
+                foreach (PointF p in HandlePoints(rc))
+                    g.FillRectangle(fill, p.X - 3f, p.Y - 3f, 6f, 6f);
             }
         }
+    }
+
+    // Corner + edge-midpoint handle positions for the selected box.
+    private static PointF[] HandlePoints(RectangleF rc)
+    {
+        float mx = rc.X + rc.Width / 2f, my = rc.Y + rc.Height / 2f;
+        return new[]
+        {
+            new PointF(rc.Left, rc.Top), new PointF(mx, rc.Top), new PointF(rc.Right, rc.Top),
+            new PointF(rc.Left, my), new PointF(rc.Right, my),
+            new PointF(rc.Left, rc.Bottom), new PointF(mx, rc.Bottom), new PointF(rc.Right, rc.Bottom),
+        };
+    }
 
     protected override void OnMouseDown(MouseEventArgs e)
     {
         base.OnMouseDown(e);
-        if (ToTemplate(e.Location) is { } pt)
+        if (e.Button != MouseButtons.Left || ToTemplate(e.Location) is not { } pt)
+            return;
+
+        // In edit mode a press on the selected box starts a (potential) drag; the
+        // click-vs-drag call is made on mouse-up so stacked-cell cycling still works.
+        if (_editMode && SelectedRegion() is { } region && Fit() is { } fit)
+        {
+            OverlayBoxHandle handle = OverlayRegionEdit.HitHandle(region, pt.X, pt.Y, HandleGrabPx / fit.Scale);
+            if (handle != OverlayBoxHandle.None)
+            {
+                _dragHandle = handle;
+                _downControl = e.Location;
+                _downRect = (region.X, region.Y, region.Width, region.Height);
+                _dragging = false;
+                Capture = true;
+                return;
+            }
+        }
+
         TemplateClicked?.Invoke(pt.X, pt.Y);
     }
 
@@ -106,6 +178,29 @@ internal sealed class WallpaperCanvas : Control
     {
         base.OnMouseMove(e);
 
+        if (_dragHandle != OverlayBoxHandle.None && Fit() is { } fit)
+        {
+            if (!_dragging &&
+                Math.Abs(e.X - _downControl.X) < DragThresholdPx &&
+                Math.Abs(e.Y - _downControl.Y) < DragThresholdPx)
+                return;
+            _dragging = true;
+
+            if (SelectedRegion() is { } region)
+            {
+                (region.X, region.Y, region.Width, region.Height) = OverlayRegionEdit.Apply(
+                    _downRect.X, _downRect.Y, _downRect.W, _downRect.H,
+                    _dragHandle,
+                    (e.X - _downControl.X) / fit.Scale,
+                    (e.Y - _downControl.Y) / fit.Scale);
+                SelectedGeometryChanged?.Invoke();
+                Invalidate();
+            }
+            return;
+        }
+
+        UpdateEditCursor(e.Location);
+
         OverlayRegion? hover = null;
         if (Template is not null && ToTemplate(e.Location) is { } pt)
             hover = OverlayHitTester.RegionsAt(Template, pt.X, pt.Y).FirstOrDefault();
@@ -117,6 +212,47 @@ internal sealed class WallpaperCanvas : Control
         }
     }
 
+    protected override void OnMouseUp(MouseEventArgs e)
+    {
+        base.OnMouseUp(e);
+        if (_dragHandle == OverlayBoxHandle.None)
+            return;
+
+        bool dragged = _dragging;
+        _dragHandle = OverlayBoxHandle.None;
+        _dragging = false;
+        Capture = false;
+
+        if (dragged)
+            GeometryCommitted?.Invoke();
+        else if (ToTemplate(e.Location) is { } pt)
+            TemplateClicked?.Invoke(pt.X, pt.Y); // a plain click: select/cycle as usual
+    }
+
+    private OverlayRegion? SelectedRegion() =>
+        _selectedRegionName is { } name ? Template?.FindRegion(name) : null;
+
+    // Resize/move cursor feedback while hovering the selected box in edit mode.
+    private void UpdateEditCursor(Point location)
+    {
+        if (!_editMode)
+            return;
+
+        OverlayBoxHandle handle = OverlayBoxHandle.None;
+        if (SelectedRegion() is { } region && Fit() is { } fit && ToTemplate(location) is { } pt)
+            handle = OverlayRegionEdit.HitHandle(region, pt.X, pt.Y, HandleGrabPx / fit.Scale);
+
+        Cursor = handle switch
+        {
+            OverlayBoxHandle.Move => Cursors.SizeAll,
+            OverlayBoxHandle.North or OverlayBoxHandle.South => Cursors.SizeNS,
+            OverlayBoxHandle.East or OverlayBoxHandle.West => Cursors.SizeWE,
+            OverlayBoxHandle.NorthWest or OverlayBoxHandle.SouthEast => Cursors.SizeNWSE,
+            OverlayBoxHandle.NorthEast or OverlayBoxHandle.SouthWest => Cursors.SizeNESW,
+            _ => Cursors.Default,
+        };
+    }
+
     // Scale-to-fit mapping between template pixels and control pixels (letterboxed).
     private (float Scale, float OffsetX, float OffsetY)? Fit()
     {

src/RioJoy.Tray/Editor/WallpaperMakerForm.cs

@@ -20,6 +20,7 @@ public sealed class WallpaperMakerForm : Form
 {
     private readonly RioProfile _profile;
     private readonly OverlayTemplate _template;
+    private readonly string? _templatePath;
     private readonly RioJoy.Overlay.SkiaOverlayRenderer _renderer = new();
     private readonly SKBitmap _baseImage;
 
@@ -27,7 +28,14 @@ public sealed class WallpaperMakerForm : Form
     private readonly Label _cellInfo = new() { AutoSize = true, Location = new Point(12, 40), MaximumSize = new Size(310, 0), Text = "Click a cell to edit it." };
     private readonly TextBox _labelBox = new() { Location = new Point(70, 74), Width = 230, Enabled = false };
     private readonly CheckBox _outlines = new() { Text = "Show cell outlines", Location = new Point(12, 104), AutoSize = true, Checked = true };
-    private readonly ListBox _list = new() { Location = new Point(12, 132), Size = new Size(306, 316), IntegralHeight = false, DrawMode = DrawMode.OwnerDrawFixed };
+    private readonly CheckBox _editBoxes = new() { Text = "Edit cell boxes", Location = new Point(150, 104), AutoSize = true };
+    private readonly NumericUpDown _numX = new() { Location = new Point(34, 130), Width = 66, Enabled = false };
+    private readonly NumericUpDown _numY = new() { Location = new Point(132, 130), Width = 66, Enabled = false };
+    private readonly NumericUpDown _numW = new() { Location = new Point(34, 156), Width = 66, Minimum = 1, Enabled = false };
+    private readonly NumericUpDown _numH = new() { Location = new Point(132, 156), Width = 66, Minimum = 1, Enabled = false };
+    private readonly Button _saveTemplate = new() { Text = "Save template", Location = new Point(204, 130), Width = 114, Enabled = false };
+    private readonly Button _reloadTemplate = new() { Text = "Reload template", Location = new Point(204, 156), Width = 114, Enabled = false };
+    private readonly ListBox _list = new() { Location = new Point(12, 188), Size = new Size(306, 260), IntegralHeight = false, DrawMode = DrawMode.OwnerDrawFixed };
     private readonly Label _hoverInfo = new() { AutoSize = true, Location = new Point(12, 456), ForeColor = SystemColors.GrayText };
     private readonly Button _import = new() { Text = "Import labels (.data)…", Location = new Point(12, 484), Width = 306 };
     private readonly Button _export = new() { Text = "Export PNG…", Location = new Point(12, 514), Width = 306 };
@@ -38,8 +46,9 @@ public sealed class WallpaperMakerForm : Form
     // Re-render shortly after typing stops rather than per keystroke.
     private readonly System.Windows.Forms.Timer _renderTimer = new() { Interval = 300 };
 
-    // Briefly flips the Save button to a confirmation, then reverts.
+    // Briefly flips a button to a confirmation, then reverts (one at a time).
     private readonly System.Windows.Forms.Timer _saveFlash = new() { Interval = 1600 };
+    private Action? _saveFlashReset;
 
     private byte[] _lastPng = Array.Empty<byte>();
     private bool _loading;
@@ -51,10 +60,16 @@ public sealed class WallpaperMakerForm : Form
     /// Directory the template's relative <see cref="OverlayTemplate.BaseImagePath"/>
     /// is resolved against (normally the folder holding the regions.json).
     /// </param>
-    public WallpaperMakerForm(RioProfile profile, OverlayTemplate template, string templateDirectory)
+    /// <param name="templatePath">
+    /// The template file itself; enables the box editor's "Save template" /
+    /// "Reload template" (cell geometry is shared by every profile). Null = the
+    /// geometry can still be edited for this session but not persisted.
+    /// </param>
+    public WallpaperMakerForm(RioProfile profile, OverlayTemplate template, string templateDirectory, string? templatePath = null)
     {
         _profile = profile ?? throw new ArgumentNullException(nameof(profile));
         _template = template ?? throw new ArgumentNullException(nameof(template));
+        _templatePath = templatePath;
         if (string.IsNullOrWhiteSpace(template.BaseImagePath))
             throw new InvalidOperationException("OverlayTemplate.BaseImagePath is not set.");
 
@@ -73,6 +88,25 @@ public sealed class WallpaperMakerForm : Form
         _canvas.Template = template;
         _canvas.TemplateClicked += OnCanvasClicked;
         _canvas.HoverChanged += r => _hoverInfo.Text = r is null ? "" : Describe(r);
+        _canvas.SelectedGeometryChanged += () => LoadGeometryFields(SelectedRegion());
+        _canvas.GeometryCommitted += () =>
+        {
+            LoadGeometryFields(SelectedRegion());
+            RenderPreview();
+        };
+
+        _numX.Maximum = _numW.Maximum = Math.Max(1, template.Width);
+        _numY.Maximum = _numH.Maximum = Math.Max(1, template.Height);
+        foreach (NumericUpDown n in new[] { _numX, _numY, _numW, _numH })
+            n.ValueChanged += OnGeometryFieldChanged;
+
+        _editBoxes.CheckedChanged += (_, _) =>
+        {
+            _canvas.EditMode = _editBoxes.Checked;
+            UpdateGeometryEnabled();
+        };
+        _saveTemplate.Click += (_, _) => SaveTemplate();
+        _reloadTemplate.Click += (_, _) => ReloadTemplate();
 
         _list.Items.AddRange(template.Regions.Select(r => (object)r.Name).ToArray());
         _list.DrawItem += DrawListItem;
@@ -90,15 +124,24 @@ public sealed class WallpaperMakerForm : Form
         _saveFlash.Tick += (_, _) =>
         {
             _saveFlash.Stop();
-            _save.Text = "Save profile";
-            _save.ForeColor = SystemColors.ControlText;
+            _saveFlashReset?.Invoke();
+            _saveFlashReset = null;
         };
 
         var side = new Panel { Dock = DockStyle.Right, Width = 330, Padding = new Padding(8), BorderStyle = BorderStyle.FixedSingle, AutoScroll = true };
         side.Controls.Add(new Label { Text = "Cells:", Location = new Point(12, 12), AutoSize = true });
         side.Controls.Add(_cellInfo);
         side.Controls.Add(new Label { Text = "Label:", Location = new Point(12, 77), AutoSize = true });
-        side.Controls.AddRange(new Control[] { _labelBox, _outlines, _list, _hoverInfo, _import, _export, _applyWallpaper, _save, _close });
+        side.Controls.Add(new Label { Text = "X:", Location = new Point(12, 133), AutoSize = true });
+        side.Controls.Add(new Label { Text = "Y:", Location = new Point(110, 133), AutoSize = true });
+        side.Controls.Add(new Label { Text = "W:", Location = new Point(12, 159), AutoSize = true });
+        side.Controls.Add(new Label { Text = "H:", Location = new Point(110, 159), AutoSize = true });
+        side.Controls.AddRange(new Control[]
+        {
+            _labelBox, _outlines, _editBoxes,
+            _numX, _numY, _numW, _numH, _saveTemplate, _reloadTemplate,
+            _list, _hoverInfo, _import, _export, _applyWallpaper, _save, _close,
+        });
 
         Controls.Add(_canvas);
         Controls.Add(side);
@@ -126,8 +169,116 @@ public sealed class WallpaperMakerForm : Form
         _labelBox.Text = _profile.OverlayLabels.TryGetValue(name, out string? text) ? text : string.Empty;
         _labelBox.Enabled = true;
         _canvas.SelectedRegionName = name;
-        _cellInfo.Text = _template.FindRegion(name) is { } r ? Describe(r) : name;
+        OverlayRegion? region = _template.FindRegion(name);
+        _cellInfo.Text = region is { } r ? Describe(r) : name;
         _loading = false;
+
+        LoadGeometryFields(region);
+        UpdateGeometryEnabled();
+    }
+
+    private OverlayRegion? SelectedRegion() =>
+        _list.SelectedItem is string name ? _template.FindRegion(name) : null;
+
+    // Reflect a region's box into the X/Y/W/H fields without triggering edits.
+    private void LoadGeometryFields(OverlayRegion? region)
+    {
+        if (region is not null)
+            _cellInfo.Text = Describe(region);
+
+        _loading = true;
+        _numX.Value = Clamp(region?.X ?? 0, _numX);
+        _numY.Value = Clamp(region?.Y ?? 0, _numY);
+        _numW.Value = Clamp(region?.Width ?? 1, _numW);
+        _numH.Value = Clamp(region?.Height ?? 1, _numH);
+        _loading = false;
+
+        static decimal Clamp(double value, NumericUpDown n) =>
+            Math.Min(n.Maximum, Math.Max(n.Minimum, (decimal)Math.Round(value)));
+    }
+
+    private void UpdateGeometryEnabled()
+    {
+        bool editing = _editBoxes.Checked;
+        bool hasRegion = SelectedRegion() is not null;
+        foreach (NumericUpDown n in new[] { _numX, _numY, _numW, _numH })
+            n.Enabled = editing && hasRegion;
+        _saveTemplate.Enabled = editing && _templatePath is not null;
+        _reloadTemplate.Enabled = editing && _templatePath is not null;
+    }
+
+    // Typed box geometry: write through to the region and re-render (debounced).
+    private void OnGeometryFieldChanged(object? sender, EventArgs e)
+    {
+        if (_loading || SelectedRegion() is not { } region)
+            return;
+
+        region.X = (double)_numX.Value;
+        region.Y = (double)_numY.Value;
+        region.Width = (double)_numW.Value;
+        region.Height = (double)_numH.Value;
+
+        _canvas.Invalidate();
+        _renderTimer.Stop();
+        _renderTimer.Start();
+    }
+
+    // Persist the (shared, all-profile) cell geometry back to the regions.json.
+    private void SaveTemplate()
+    {
+        if (_templatePath is null)
+            return;
+
+        try
+        {
+            OverlayTemplateStore.Save(_template, _templatePath);
+            Flash(_saveTemplate, "Saved ✓");
+        }
+        catch (Exception ex)
+        {
+            MessageBox.Show(this, $"Could not save the template:\n{ex.Message}",
+                "RIOJoy", MessageBoxButtons.OK, MessageBoxIcon.Warning);
+        }
+    }
+
+    // Discard unsaved box edits by re-reading the cell geometry from disk (labels
+    // are untouched — they live in the profile, not the template).
+    private void ReloadTemplate()
+    {
+        if (_templatePath is null)
+            return;
+
+        try
+        {
+            OverlayTemplate fresh = OverlayTemplateStore.Load(_templatePath);
+            foreach (OverlayRegion r in _template.Regions)
+            {
+                if (fresh.FindRegion(r.Name) is { } f)
+                    (r.X, r.Y, r.Width, r.Height) = (f.X, f.Y, f.Width, f.Height);
+            }
+
+            LoadGeometryFields(SelectedRegion());
+            RenderPreview();
+        }
+        catch (Exception ex)
+        {
+            MessageBox.Show(this, $"Could not reload the template:\n{ex.Message}",
+                "RIOJoy", MessageBoxButtons.OK, MessageBoxIcon.Warning);
+        }
+    }
+
+    // Briefly show a confirmation on a button, then restore its caption.
+    private void Flash(Button button, string confirmation)
+    {
+        _saveFlash.Stop();
+        _saveFlashReset?.Invoke();
+
+        string original = button.Text;
+        Color originalColor = button.ForeColor;
+        button.Text = confirmation;
+        button.ForeColor = Color.ForestGreen;
+        _saveFlashReset = () => { button.Text = original; button.ForeColor = originalColor; };
+        _saveFlash.Start();
     }
 
     // A click on the preview: select the cell there, cycling through stacked cells.
@@ -323,18 +474,13 @@ public sealed class WallpaperMakerForm : Form
         try
         {
             Saved?.Invoke(_profile);
-            _save.Text = "Saved ✓";
-            _save.ForeColor = Color.ForestGreen;
+            Flash(_save, "Saved ✓");
         }
         catch (Exception ex)
         {
-            _save.Text = "Save failed";
-            _save.ForeColor = Color.Firebrick;
             MessageBox.Show(this, $"Could not save the profile:\n{ex.Message}",
                 "RIOJoy", MessageBoxButtons.OK, MessageBoxIcon.Warning);
         }
-        _saveFlash.Stop();
-        _saveFlash.Start();
     }
 
     private static string SafeFileName(string name)

src/RioJoy.Tray/TrayApplicationContext.cs

@@ -195,7 +195,7 @@ internal sealed class TrayApplicationContext : ApplicationContext
             OverlayTemplate template = OverlayTemplateStore.Load(path!);
             string templateDir = Path.GetDirectoryName(Path.GetFullPath(path!)) ?? ".";
 
-            var maker = new WallpaperMakerForm(profile, template, templateDir);
+            var maker = new WallpaperMakerForm(profile, template, templateDir, path);
             maker.Saved += _ => ConfigStore.Save(_config, ConfigPath);
             maker.Show();
         }

tests/RioJoy.Core.Tests/Overlay/OverlayRegionEditTests.cs

@@ -0,0 +1,69 @@
+using RioJoy.Core.Overlay;
+using Xunit;
+
+namespace RioJoy.Core.Tests.Overlay;
+
+public class OverlayRegionEditTests
+{
+    private static OverlayRegion Box() => new() { Name = "r", X = 100, Y = 50, Width = 200, Height = 80 };
+
+    [Theory]
+    [InlineData(100, 50, OverlayBoxHandle.NorthWest)]
+    [InlineData(300, 50, OverlayBoxHandle.NorthEast)]
+    [InlineData(100, 130, OverlayBoxHandle.SouthWest)]
+    [InlineData(300, 130, OverlayBoxHandle.SouthEast)]
+    [InlineData(200, 50, OverlayBoxHandle.North)]
+    [InlineData(200, 130, OverlayBoxHandle.South)]
+    [InlineData(100, 90, OverlayBoxHandle.West)]
+    [InlineData(300, 90, OverlayBoxHandle.East)]
+    [InlineData(200, 90, OverlayBoxHandle.Move)]
+    [InlineData(0, 0, OverlayBoxHandle.None)]
+    public void HitHandle_ResolvesEachZone(double x, double y, OverlayBoxHandle expected)
+    {
+        Assert.Equal(expected, OverlayRegionEdit.HitHandle(Box(), x, y, tolerance: 4));
+    }
+
+    [Fact]
+    public void HitHandle_ToleranceExtendsOutsideTheBox()
+    {
+        Assert.Equal(OverlayBoxHandle.NorthWest, OverlayRegionEdit.HitHandle(Box(), 97, 47, 4));
+        Assert.Equal(OverlayBoxHandle.None, OverlayRegionEdit.HitHandle(Box(), 94, 44, 4));
+    }
+
+    [Fact]
+    public void Apply_MoveShiftsWithoutResizing()
+    {
+        var r = OverlayRegionEdit.Apply(100, 50, 200, 80, OverlayBoxHandle.Move, 15, -10);
+
+        Assert.Equal((115d, 40d, 200d, 80d), r);
+    }
+
+    [Fact]
+    public void Apply_EastGrowsWidthOnly()
+    {
+        var r = OverlayRegionEdit.Apply(100, 50, 200, 80, OverlayBoxHandle.East, 30, 99);
+
+        Assert.Equal((100d, 50d, 230d, 80d), r);
+    }
+
+    [Fact]
+    public void Apply_NorthWestMovesOriginAndResizes()
+    {
+        var r = OverlayRegionEdit.Apply(100, 50, 200, 80, OverlayBoxHandle.NorthWest, 10, 20);
+
+        Assert.Equal((110d, 70d, 190d, 60d), r);
+    }
+
+    [Fact]
+    public void Apply_ClampsToMinSize_OppositeEdgeStaysPut()
+    {
+        var r = OverlayRegionEdit.Apply(100, 50, 200, 80, OverlayBoxHandle.West, 500, 0, minSize: 4);
+
+        Assert.Equal(296, r.X, 6);        // right edge (300) minus min width
+        Assert.Equal(4, r.Width, 6);
+
+        var s = OverlayRegionEdit.Apply(100, 50, 200, 80, OverlayBoxHandle.South, 0, -500, minSize: 4);
+        Assert.Equal(50, s.Y, 6);
+        Assert.Equal(4, s.Height, 6);
+    }
+}