Fix stale hover latch on drag release, tooltip anchor, border off-by-one; pin gutter golden test, drop DPI framing

src/shell/instrument/editor_input.cpp

@@ -79,6 +79,11 @@ void ReaSamplerEditor::onMouseUp(int x, int y) {
     drag_ = DragKind::kNone;
     dragParamId_ = -1;
     curvePointIndex_ = -1;
+    // hover_ is deliberately not re-resolved during a drag (see resolveHover's caller), so it
+    // still names wherever the drag started. Re-resolve now against the release position, for
+    // every drag kind — otherwise the next paint latches a stale hover (wrong note name/tooltip,
+    // wrong control outline) until the next WM_MOUSEMOVE.
+    resolveHover(x, y);
     // A scrollbar drag is transient UI (no parameter change), and the processor-side knobs
     // (the preview-velocity -2 sentinel, voice count, master gain) are per-instance settings
     // that don't reload the instrument. Master gain is an atomic the audio thread reads

src/shell/instrument/editor_input_chrome.cpp

@@ -75,7 +75,6 @@ bool ReaSamplerEditor::mouseDownChrome(const FaceLayout& fl, int x, int y) {
         const StripLayout sl = layoutStrip(cr.rootStrip.width, cr.rootStrip.height);
         if (keyAtPoint(sl, x - cr.rootStrip.x, y - cr.rootStrip.y) >= 0) {
             drag_ = DragKind::kRootMarker;
-            dragStartX_ = x;
             dragStartParams_ = params_;
             onMouseMove(x, y);
             return true;

src/shell/instrument/editor_paint_chrome.cpp

@@ -205,13 +205,16 @@ void ReaSamplerEditor::paintChromeTooltip(LICE_IBitmap* bmp, const FaceLayout& f
 
     const std::string label = noteName(hover_.index);
     const int textW = static_cast<int>(label.size()) * kTooltipCharPx;
-    const TooltipBox tb = computeTooltip(area.x + key.x, area.y + key.y, key.width, key.height,
+    // Anchor y/h to the whole strip row, not the hovered key: a black key (18px) is shorter
+    // than a white key (30px), and anchoring to the key rect placed the chip 12px higher for
+    // black keys — landing on the keyboard's bottom edge and, near the root, on the badge.
+    const TooltipBox tb = computeTooltip(area.x + key.x, area.y, key.width, area.height,
                                          textW, kTooltipTextH, w, h, TooltipSpec{});
     if (tb.empty()) return;
 
     const Rect box = Rect::ltrb(tb.x, tb.y, tb.x + tb.width, tb.y + tb.height);
     fillSurface(bmp, toKitBox(box), Role::BgCell, InteractionState::Hover);
-    LICE_DrawRect(bmp, box.x, box.y, box.width, box.height,
+    LICE_DrawRect(bmp, box.x, box.y, box.width - 1, box.height - 1,
                   toLice(roleColor(Role::LineHairline)), 1.0f, 0);
     kitTextCentered(bmp, box, label.c_str(), Font::Label, Role::TextPrimary);
 }