@

fix(D.2b): arrow swap, centered menu text, scrollbar-to-top, Send caption

- scroll arrows: native sprites are opposite (0x06004C6C up / 0x06004C69 down) per live
  visual — swap the assignment, drop the V-flip.
- menu labels centered vertically in each 17px row (was top-aligned, looked corrupt).
- scrollbar pulled up to the panel top so the top arrow meets the window border and the
  max/min button lines up with it (the 6px dat offset left a gap after the resize-bar reclaim).
- Send button: the dat sprite 0x06001915 is a blank gold frame (export-confirmed), so add a
  generic optional Label/LabelFont to UiDatElement and draw "Send" centered on it.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
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src/AcDream.App/UI/Layout/UiDatElement.cs

@@ -87,21 +87,36 @@ public sealed class UiDatElement : UiElement
         return false;
     }
 
+    /// <summary>Optional centered text label drawn over the sprite (e.g. the "Send"
+    /// button face whose dat sprite is a blank frame). Null = sprite only.</summary>
+    public string? Label { get; set; }
+    /// <summary>Dat font for <see cref="Label"/>. Required for the label to draw.</summary>
+    public UiDatFont? LabelFont { get; set; }
+    /// <summary>Label color (default white).</summary>
+    public Vector4 LabelColor { get; set; } = Vector4.One;
+
     protected override void OnDraw(UiRenderContext ctx)
     {
         var (file, _) = ActiveMedia();
-        if (file == 0) return;
+        if (file != 0)
+        {
+            var (tex, tw, th) = _resolve(file);
+            if (tex != 0 && tw != 0 && th != 0)
+            {
+                // Normal → TILE at native size on both axes (UV-repeat; GL_REPEAT-wrapped UI
+                // texture), matching ImgTex::TileCSI. Overlay/Alphablend use the same blit (the
+                // sprite shader already alpha-blends). No Stretch mode exists in DrawModeType.
+                ctx.DrawSprite(tex, 0, 0, Width, Height, 0, 0, Width / tw, Height / th, Vector4.One);
+            }
+        }
 
-        var (tex, tw, th) = _resolve(file);
-        if (tex == 0 || tw == 0 || th == 0) return;
-
-        // Normal → TILE at native size on both axes (UV-repeat; GL_REPEAT-wrapped UI texture),
-        // matching ImgTex::TileCSI. Overlay/Alphablend are the same blit with a blend state; the
-        // sprite shader already alpha-blends, so the quad is identical for all draw modes in Plan 1.
-        // (No Stretch mode exists in DatReaderWriter.Enums.DrawModeType.)
-        // DrawMode is not yet branched here — Plan 2 can add per-mode behavior if needed.
-        float u1 = Width / tw;
-        float v1 = Height / th;
-        ctx.DrawSprite(tex, 0, 0, Width, Height, 0, 0, u1, v1, Vector4.One);
+        // Centered text label over the sprite (retail draws button captions as text;
+        // their dat sprites are blank frames).
+        if (Label is { Length: > 0 } label && LabelFont is { } lf)
+        {
+            float tx = (Width - lf.MeasureWidth(label)) * 0.5f;
+            float ty = (Height - lf.LineHeight) * 0.5f;
+            ctx.DrawStringDat(lf, label, tx, ty, LabelColor);
+        }
     }
 }