fix(ui): stop status-bar tooltips flashing on and off

The strip's built-in item tooltips open below the cursor. With the window
maximized the strip is at the bottom of the screen, so Windows pushes the
tooltip back over the cursor; the strip then sees a mouse leave, hides it,
re-shows it on the next hover, and it flickers. Show the tooltips above the
strip instead.

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

OpenNest/Forms/MainForm.Designer.cs

@@ -21,7 +21,10 @@ namespace OpenNest.Forms
                 components.Dispose();
             }
             if (disposing)
+            {
                 updaterStatus?.Dispose();
+                statusStripToolTips?.Dispose();
+            }
             base.Dispose(disposing);
         }
 

OpenNest/Forms/MainForm.cs

@@ -112,7 +112,7 @@ namespace OpenNest.Forms
             Icon = Resources.app_icon;
             statusStrip1.Items.Insert(statusStrip1.Items.IndexOf(materialStatusLabel) + 1, ledgerStatusLabel);
             ledgerStatusLabel.Click += LedgerStatusLabel_Click;
-            statusStrip1.ShowItemToolTips = true; // The hold list lives in the ledger label's tooltip.
+            statusStripToolTips = new StatusStripToolTips(statusStrip1); // The hold list lives in the ledger label's tooltip.
             statusBar = new MainStatusBar(statusLabel1, locationStatusLabel, selectionStatusLabel,
                 machineStatusLabel, materialStatusLabel, plateUtilStatusLabel, ledgerStatusLabel);
             toolStrip1.Items.Add(CreateActionButton("btnCutPlanner", "Plan Cutting",
@@ -168,6 +168,7 @@ namespace OpenNest.Forms
         }
 
         private UpdaterStatus updaterStatus;
+        private StatusStripToolTips statusStripToolTips;
 
         private void InitializeHelpMenu()
         {

OpenNest/Forms/StatusStripToolTips.cs

@@ -0,0 +1,94 @@
+using System;
+using System.Drawing;
+using System.Windows.Forms;
+
+namespace OpenNest.Forms
+{
+    /// <summary>
+    /// Shows a status strip's item tooltips above the strip. The strip's own tooltips open
+    /// below the cursor; at the bottom of the screen Windows pushes them back over the
+    /// cursor, the strip sees a mouse leave and hides them, and they flash on and off.
+    /// </summary>
+    internal sealed class StatusStripToolTips : IDisposable
+    {
+        private const int Gap = 2;
+
+        private readonly ToolStrip strip;
+        private readonly ToolTip toolTip = new();
+        private readonly Timer hoverTimer = new() { Interval = SystemInformation.MouseHoverTime };
+        private ToolStripItem hoverItem;
+        private string shownText;
+
+        public StatusStripToolTips(ToolStrip strip)
+        {
+            this.strip = strip;
+            strip.ShowItemToolTips = false;
+            strip.MouseMove += Strip_MouseMove;
+            strip.MouseLeave += Strip_MouseLeave;
+            strip.MouseDown += Strip_MouseDown;
+            hoverTimer.Tick += HoverTimer_Tick;
+        }
+
+        public void Dispose()
+        {
+            hoverTimer.Dispose();
+            toolTip.Dispose();
+        }
+
+        private void Strip_MouseMove(object sender, MouseEventArgs e)
+        {
+            var item = strip.GetItemAt(e.Location);
+            if (item == hoverItem)
+                return;
+
+            Hide();
+            hoverItem = item;
+            if (!string.IsNullOrEmpty(item?.ToolTipText))
+                hoverTimer.Start();
+        }
+
+        private void Strip_MouseLeave(object sender, EventArgs e)
+        {
+            Hide();
+            hoverItem = null;
+        }
+
+        // The next move re-arms the hover, so a click that changes the text (a hold refresh) shows the new tip.
+        private void Strip_MouseDown(object sender, MouseEventArgs e)
+        {
+            Hide();
+            hoverItem = null;
+        }
+
+        private void HoverTimer_Tick(object sender, EventArgs e)
+        {
+            hoverTimer.Stop();
+            Show();
+        }
+
+        private void Show()
+        {
+            var text = hoverItem?.ToolTipText;
+            if (string.IsNullOrEmpty(text))
+            {
+                Hide();
+                return;
+            }
+
+            // The tooltip draws its text in the status font plus a few pixels of border and margin.
+            var height = TextRenderer.MeasureText(text, SystemFonts.StatusFont).Height + 10;
+            toolTip.Show(text, strip, hoverItem.Bounds.Left, -height - Gap);
+            shownText = text;
+        }
+
+        private void Hide()
+        {
+            hoverTimer.Stop();
+            if (shownText == null)
+                return;
+
+            toolTip.Hide(strip);
+            shownText = null;
+        }
+    }
+}