L5: dock-panel button refinements — overflow menu, tooltips, opposite-mode tag buttons

Top-bar rare-capture variants move to a right-anchored More popup; short faces gain
hover-delay full-name tooltips (prefix stripped); bottom bar becomes four opposite-mode
Item/Track tag buttons + Show Both (Toggle/Activates dropped); wider cluster gaps. New
pure overflow_menu/mode_enable/tooltip modules, CTest-covered. Same actions, same contract.

src/overflow_menu.h

@@ -0,0 +1,87 @@
+#pragma once
+// overflow_menu — the REAPER-free layout math behind the bank_panel TOP toolbar's "⋯ / More"
+// overflow-menu button (Phase L, L5, refinement 1). The rare capture variants (Batch Items /
+// Batch Razor / Capture RT) move OFF the always-visible top bar into a popup opened by a small
+// square button pinned to the FAR RIGHT of the top toolbar band. This module owns two things,
+// both unit-tested outside the DAW:
+//   * WHERE the More button sits in the top toolbar band (right-anchored, vertically inset);
+//   * the horizontal RESERVE the action_bar must leave for it, so the frequent buttons never
+//     run under the menu button (the shell shrinks the action_bar's usable width by this).
+// The popup itself (TrackPopupMenu) + the command dispatch is shell — a transient OS menu, not
+// panel chrome (brief §1: "a REAPER/host popup menu is acceptable"). Only the button
+// geometry + hit-test live here.
+//
+// PURE MODULE: NO REAPER types, NO SWELL, NO LICE, NO vendor/ includes. Standard library only.
+// Mirror of prune_button / mode_switch. The bar rect type it consumes mirrors action_bar's
+// ActionBarRect shape but is named distinctly to avoid coupling the two modules.
+
+namespace reasampler {
+
+// The toolbar band the button is drawn into, top-left origin (SWELL/LICE convention). The
+// shell derives this from topToolbarRect(). A distinct type from action_bar::ActionBarRect so
+// this module stands alone (same shape; deliberate — the two modules are not coupled).
+struct MenuBarRect {
+    int x = 0;
+    int y = 0;
+    int width = 0;
+    int height = 0;
+
+    bool operator==(const MenuBarRect& o) const {
+        return x == o.x && y == o.y && width == o.width && height == o.height;
+    }
+};
+
+// The More button's pixel rectangle within the band, top-left origin. A zero-area rect
+// (width <= 0 or height <= 0) means "no button" — the band is degenerate or too narrow to
+// place the button clear of its left inset; the caller must not draw or hit-test it. The
+// three variants stay reachable via their bindable commands, so a suppressed button is
+// graceful, not a lost affordance.
+struct MenuButtonRect {
+    int x = 0;
+    int y = 0;
+    int width = 0;
+    int height = 0;
+
+    bool empty() const { return width <= 0 || height <= 0; }
+
+    bool operator==(const MenuButtonRect& o) const {
+        return x == o.x && y == o.y && width == o.width && height == o.height;
+    }
+};
+
+// Layout inputs for the More button, in pixels. Defaults match the bank_panel top-toolbar
+// metrics; the shell passes its own so draw and hit-test share one source of truth.
+//   * buttonWidth   — the button's fixed width (a compact square-ish glyph button).
+//   * rightInset    — gap from the band's right edge to the button's right edge.
+//   * verticalInset — top/bottom gap inside the band (shorter than the band so it reads as a
+//                     raised control, matching the action_bar buttons' verticalInset).
+//   * minLeftInset  — the button's left edge must stay at least this far from the band left
+//                     edge; if it would encroach past this, computeMenuButton yields an empty
+//                     rect (button suppressed).
+struct MenuButtonSpec {
+    int buttonWidth = 28;
+    int rightInset = 6;
+    int verticalInset = 3;
+    int minLeftInset = 40;
+};
+
+// The horizontal reserve (px) the action_bar must leave at the band's right so its buttons
+// never run under the More button: the button width + both insets (right gap + a matching
+// left breathing gap equal to rightInset). The shell subtracts this from the action_bar rect's
+// width before laying out slots. Returns 0 for a degenerate band (nothing to reserve).
+int menuButtonReserve(const MenuBarRect& bar, const MenuButtonSpec& spec);
+
+// Computes the More button's rect within `bar` per `spec`. Right-anchored: the button's right
+// edge is bar.x + bar.width - rightInset, its width is buttonWidth, vertically centred by
+// verticalInset. Returns an EMPTY rect when: the band is degenerate (width/height <= 0), the
+// buttonWidth is non-positive, OR the resulting left edge would fall closer to the band left
+// than minLeftInset. A thin band clamps the button height to the band's own rather than going
+// negative (mirror of computePruneButton).
+MenuButtonRect computeMenuButton(const MenuBarRect& bar, const MenuButtonSpec& spec);
+
+// True iff the point (px, py) (SWELL/LICE top-left client coords) falls inside `button`.
+// Half-open bounds [x, x+width) x [y, y+height) — matches computeMenuButton so draw and
+// hit-test agree on the same pixels. An empty button never claims a point (always false).
+bool hitTestMenuButton(int px, int py, const MenuButtonRect& button);
+
+} // namespace reasampler