@@ -959,12 +959,14 @@ static std::vector<std::pair<std::string, int>> lineGroupMbFiles(Scene *s, const
 // A line area's "Show point-cloud" (90_c_api.cpp): the window's swath soundings inside `ring` in a view of
 // their own, with their own 3D Soundings
 static void mbShowAreaCloud(Scene *s, const std::vector<std::array<double, 3>> &ring);
+// ...and a navigation track's (or a group of tracks'): the soundings of those swath files, the same view
+static void mbShowFilesCloud(Scene *s, const QStringList &files);
 #endif
 // A point cloud's Scene Objects menus (50_scene.cpp): its master handle and its "Points" row
 static void cloudObjectMenu(Scene *s, const QPoint &gp);
 static void cloudPointsMenu(Scene *s, const QPoint &gp);
 static void addMbSystemMenu(QMenu &m, const std::vector<std::string> &navs, QWidget *parent = nullptr,
-                            const std::vector<std::pair<std::string, int>> &own = {});
+                            const std::vector<std::pair<std::string, int>> &own = {}, Scene *s = nullptr);
 static void overlayBuildFill(Overlay &ov);                                 // filled overlay's triangles (50_scene.cpp)
 static bool overlayActorFilled(Scene *s, vtkActor *a);                     // ...is this actor one? (50_scene.cpp)
 static void vwSaveProduct(Scene *s, const std::string &key);               // Vector Wizard product -> SVG/EPS/PDF (50_scene.cpp)
 
@@ -3251,7 +3251,7 @@ static void rebuildSceneObjects(Scene *s) {
 				QAction *aCpt = nullptr, *aBlack = nullptr;
 				// A group of MB-System navigation tracks: mbgrdviz's Action menu editors, on every track
 				// of the group (each submenu item does its own work, so `pick` matches nothing below).
-				addMbSystemMenu(m, lineGroupMbNavs(s, gn), s->win, lineGroupMbFiles(s, gn));
+				addMbSystemMenu(m, lineGroupMbNavs(s, gn), s->win, lineGroupMbFiles(s, gn), s);
 				QAction *aVw = vwKey.empty() ? nullptr : m.addAction("Save as SVG / EPS / PDF…");
 				if (aVw) m.addSeparator();
 				if (cptable) {
 
@@ -1261,8 +1261,13 @@ static std::vector<std::string> lineGroupMbNavs(Scene *s, const std::string &gna
 #ifdef GMTVTK_MBGRDVIZ
 static MbGrdVizHost mbgrdvizViewerHost();   // 90_c_api.cpp
 #endif
+//
+// "Show point-cloud" goes in the same submenu, for tracks whose swath file is part of window `s`'s point
+// cloud (a dropped swath file's navigation): the soundings of THAT file in the view a line area's
+// "Show point-cloud" opens. Built here, the one place the submenu is made, so a single track and its
+// group's handle both get it.
 static void addMbSystemMenu(QMenu &m, const std::vector<std::string> &navs, QWidget *parent,
-                            const std::vector<std::pair<std::string, int>> &own) {
+                            const std::vector<std::pair<std::string, int>> &own, Scene *s) {
 #ifdef GMTVTK_MBGRDVIZ
 	std::vector<std::string> known;
 	for (const std::string &n : navs)
@@ -1285,9 +1290,17 @@ static void addMbSystemMenu(QMenu &m, const std::vector<std::string> &navs, QWid
 				mbRunNavEditor(mbgrdvizViewerHost(), parent, which, files, formats);
 			});
 	}
+#ifdef GMTVTK_MBEDITVIZ
+	QStringList ownFiles;
+	for (const auto &f : own) ownFiles << QString::fromStdString(f.first);
+	if (s && !ownFiles.isEmpty() && mb3dsdgHasCloudFiles(s, ownFiles)) {
+		mb->addSeparator();
+		mb->addAction("Show point-cloud", [s, ownFiles]() { mbShowFilesCloud(s, ownFiles); });
+	}
+#endif
 	m.addSeparator();
 #else
-	(void)m; (void)navs; (void)parent; (void)own;
+	(void)m; (void)navs; (void)parent; (void)own; (void)s;
 #endif
 }
 
@@ -1363,7 +1376,7 @@ static void popupLineObjectMenu(Scene *s, const LineRef &lr, const QString &name
 		std::vector<std::pair<std::string, int>> own;
 		if (!ovp->mbFile.empty())
 			own.push_back({ovp->mbFile, ovp->mbFormat});
-		addMbSystemMenu(m, { ovp->mbNav }, s->win, own);
+		addMbSystemMenu(m, { ovp->mbNav }, s->win, own, s);
 	}
 
 	// EVERY nested rectangle carries the nesting actions at the TOP of the menu, so the chain can
 
@@ -2585,17 +2585,11 @@ GMTVTK_API int gmtvtk_mb_tag_cloud_grid_h(void *handle, const char *name) {
 // A line area's "Show point-cloud": the window's swath soundings inside the area, in a NEW point-cloud
 // window (gmtvtk_view_points, the window every point cloud gets) with its own 3D Soundings pane
 // (mb3dsdgOpenAreaCloud). Closing that window is its pane's Discard.
-static void mbShowAreaCloud(Scene *s, const std::vector<std::array<double, 3>> &ring) {
-	if (!sceneAlive(s) || ring.size() < 4)
-		return;
-	std::vector<double> xy;
-	const size_t n = (ring.front() == ring.back()) ? ring.size() - 1 : ring.size();   // the closing duplicate
-	for (size_t i = 0; i < n; i++) {
-		xy.push_back(ring[i][0]);
-		xy.push_back(ring[i][1]);
-	}
+// The window a sub-cloud view (an area's, a track's) opens in: gmtvtk_view_points, the window every
+// point cloud gets, framed on the soundings it is given. ONE maker and ONE closer for both views.
+static std::function<void *(const double *, int, const QString &)> mbSubCloudWindowMaker(Scene *s) {
 	const int geog = s->baseGeog ? 1 : 0;
-	auto makeWindow = [geog](const double *xyz, int np, const QString &title) -> void * {
+	return [geog](const double *xyz, int np, const QString &title) -> void * {
 		double x0 = xyz[0], x1 = xyz[0], y0 = xyz[1], y1 = xyz[1];
 		for (int i = 1; i < np; i++) {
 			x0 = std::min(x0, xyz[3 * i]);  x1 = std::max(x1, xyz[3 * i]);
@@ -2604,11 +2598,40 @@ static void mbShowAreaCloud(Scene *s, const std::vector<std::array<double, 3>> &
 		return gmtvtk_view_points(xyz, np, nullptr, nullptr, 0, x0, x1, y0, y1, geog, 3.0, 1.0, 0.0, 0.0,
 		                          title.toUtf8().constData());
 	};
-	auto closeWin = [](void *w) { if (sceneAlive(static_cast<Scene *>(w))) gmtvtk_close(w); };
+}
+static void mbSubCloudWindowClose(void *w) { if (sceneAlive(static_cast<Scene *>(w))) gmtvtk_close(w); }
+
+static void mbShowAreaCloud(Scene *s, const std::vector<std::array<double, 3>> &ring) {
+	if (!sceneAlive(s) || ring.size() < 4)
+		return;
+	std::vector<double> xy;
+	const size_t n = (ring.front() == ring.back()) ? ring.size() - 1 : ring.size();   // the closing duplicate
+	for (size_t i = 0; i < n; i++) {
+		xy.push_back(ring[i][0]);
+		xy.push_back(ring[i][1]);
+	}
 	QApplication::setOverrideCursor(Qt::WaitCursor);
-	mb3dsdgOpenAreaCloud(s, xy.data(), int(xy.size() / 2), makeWindow, closeWin);
+	mb3dsdgOpenAreaCloud(s, xy.data(), int(xy.size() / 2), mbSubCloudWindowMaker(s), mbSubCloudWindowClose);
 	QApplication::restoreOverrideCursor();
 }
+
+// A navigation track's "Show point-cloud" (its "MB-System" submenu, addMbSystemMenu): the soundings of
+// its swath file(s), in the same view an area gets. Accept / Discard / the parent's pane: the same.
+static void mbShowFilesCloud(Scene *s, const QStringList &files) {
+	if (!sceneAlive(s) || files.isEmpty())
+		return;
+	QApplication::setOverrideCursor(Qt::WaitCursor);
+	mb3dsdgOpenFileCloud(s, files, mbSubCloudWindowMaker(s), mbSubCloudWindowClose);
+	QApplication::restoreOverrideCursor();
+}
+// The same from the host: window `handle`'s cloud, the soundings of the swath file `file`. 1 = opened
+GMTVTK_API int gmtvtk_mb_file_cloud_h(void *handle, const char *file) {
+	Scene *s = static_cast<Scene *>(handle);
+	if (!sceneAlive(s) || !file || !*file)
+		return 0;
+	mbShowFilesCloud(s, QStringList{ QString::fromUtf8(file) });
+	return mb3dsdgAreaOpen() ? 1 : 0;
+}
 // The same "Show point-cloud" from coordinates: the soundings of window `handle`'s swath cloud inside the
 // polygon of n x,y vertices (true coords). 1 = the area window and its pane opened
 GMTVTK_API int gmtvtk_mb_area_cloud_h(void *handle, const double *xy, int n) {
@@ -2626,6 +2649,11 @@ GMTVTK_API int gmtvtk_mb_area_cloud_h(void *handle, const double *xy, int n) {
 GMTVTK_API int gmtvtk_mb_soundings_counts(int *out) {
 	return (out && mb3dsdgCounts(&out[0], &out[1], &out[2])) ? 1 : 0;
 }
+// The open 3D Soundings pane's buttons that are shown: bit 0 CUBE filter, bit 1 Gridding, bit 2 Discard
+// (an area / track view). -1 = no pane
+GMTVTK_API int gmtvtk_mb_pane_buttons() {
+	return mb3dsdgPaneButtons();
+}
 // View > Show flagged of the open 3D Soundings view, through its menu entry. 1 = done
 GMTVTK_API int gmtvtk_mb_soundings_show_flagged(int on) {
 	return mb3dsdgSetShowFlagged(on != 0) ? 1 : 0;
@@ -3092,7 +3120,7 @@ GMTVTK_API int gmtvtk_mbgrdviz_track_menu_test(void *handle, const char *element
 				break;
 			}
 	QMenu m;
-	addMbSystemMenu(m, navs, s->win, own);
+	addMbSystemMenu(m, navs, s->win, own, s);
 	std::string items;
 	int n = 0;
 	for (QAction *a : m.actions())
@@ -7402,10 +7430,16 @@ GMTVTK_API int gmtvtk_ecmwf_dialog_test(void *handle, const char *path) {
 // out here for a scene that is perfectly alive. The Scene struct is byte-identical between the two
 // dlls (same source, same compiler), so adopting the pointer is the same mirroring the callback
 // registrations already do.
+static void testBorrowScene(Scene *s);   // below: borrow, given back when the window goes
+// Does THIS dll still count `scene` as a live window? Pointer comparison only -- safe to ask about a
+// window that is already gone, which is the point: after its window closes the answer must be 0.
+GMTVTK_API int gmtvtk_scene_borrowed_test(void *scene) {
+	return g_scenes.count(static_cast<Scene *>(scene)) ? 1 : 0;
+}
 GMTVTK_API int gmtvtk_scene_adopt_test(void *scene) {
 	Scene *s = static_cast<Scene *>(scene);
 	if (!s) return 0;
-	g_scenes.insert(s);
+	testBorrowScene(s);
 	return 1;
 }
 
@@ -8040,6 +8074,20 @@ GMTVTK_API void *gmtvtk_open_empty(const char *title);   // defined below; forwa
 //
 // ONE function does the borrowing, for every hook, so no site can forget the giving-back half. A
 // repeat open on the same dialog just connects again — the handler is idempotent.
+// The borrowing for a hook that has no dialog slot to tie it to (a scene adopted as it is, or a dialog
+// kept in a per-window registry rather than a g_*TestDlg pointer): the borrowed Scene is given back when
+// its WINDOW is destroyed. Without this a closed window stays "alive" here for ever, and the next thing
+// in this dll that walks g_scenes -- rebuildSceneObjects -> swipeRefreshAvailability ->
+// linkPartnerWindows -- reads the freed Scene: std::bad_alloc / SIGSEGV on Linux and macOS (2026-10-07,
+// the grdlandmask parking test right after the DGT one), silently "fine" on Windows.
+static void testBorrowScene(Scene *s) {
+	if (!s) return;
+	g_scenes.insert(s);
+	static std::unordered_set<Scene *> wired;      // one give-back per window, however often borrowed
+	if (s->win && wired.insert(s).second)
+		QObject::connect(s->win, &QObject::destroyed, [s]() { g_scenes.erase(s); wired.erase(s); });
+}
+
 template <class T>
 static void testBorrowWindow(Scene *s, T **slot) {
 	if (!s) return;
@@ -8672,7 +8720,7 @@ GMTVTK_API int gmtvtk_movie_open_dialog_test(void *handle) {
 	ensureApp();
 	Scene *s = static_cast<Scene *>(handle);
 	if (!s || !s->win) return 0;
-	g_scenes.insert(s);
+	testBorrowScene(s);
 	return gmtvtk_open_movie_dialog_h(s);
 }
 // The X, driven the way a user drives it.
@@ -8712,7 +8760,7 @@ GMTVTK_API int gmtvtk_dgt_open_dialog_test(void *handle) {
 	ensureApp();
 	Scene *s = static_cast<Scene *>(handle);
 	if (!s || !s->win) return 0;
-	g_scenes.insert(s);
+	testBorrowScene(s);
 	DgtLidarDialog *w = dgtTestDlg(handle);
 	if (w) w->unpark();
 	else {
@@ -8783,7 +8831,7 @@ GMTVTK_API int gmtvtk_landmask_open_dialog_test(void *handle) {
 	ensureApp();
 	Scene *s = static_cast<Scene *>(handle);
 	if (!s || !s->win) return 0;
-	g_scenes.insert(s);
+	testBorrowScene(s);
 	const int ok = openGrdLandmaskDialog(s->win, s);
 	QApplication::processEvents();
 	return ok;
 
@@ -8,6 +8,7 @@
 #include "mb3dsoundings_window.h"
 #include "mbeditviz.h"
 
+#include <QDir>
 #include <QFileInfo>
 #include <QMessageBox>
 #include <QTimer>
@@ -348,23 +349,19 @@ int mb3dsdgEsfFlag(const MbEditHost &host, const QStringList &files, const doubl
 	return failed.isEmpty() ? n : -1;
 }
 
-bool mb3dsdgOpenAreaCloud(void *parentScene, const double *ring, int nring,
-                          const std::function<void *(const double *xyz, int n, const QString &title)> &makeWindow,
-                          const std::function<void(void *)> &closeWin) {
+// THE sub-cloud view, whatever picks its soundings: a line area's "Show point-cloud" (the soundings
+// inside it) and a navigation track's (the soundings of its file). `keep` says which of the parent's
+// soundings go; everything else -- the window, the pane, Accept / Discard, the parent stepping aside --
+// is this one function, so the two views cannot drift apart. `none` is said when nothing is kept.
+static bool openSubCloud(void *parentScene, const std::function<bool(const mb3dsoundings_sounding_struct &)> &keep,
+                         const QString &suffix, const QString &none,
+                         const std::function<void *(const double *xyz, int n, const QString &title)> &makeWindow,
+                         const std::function<void(void *)> &closeWin) {
 	Cloud *p = g_cloud;
-	if (!p || p->scene != parentScene || !ring || nring < 3 || !makeWindow)
+	if (!p || p->scene != parentScene || !keep || !makeWindow)
 		return false;
-	auto inside = [ring, nring](double x, double y) {   // even-odd rule over the ring (x,y pairs)
-		bool in = false;
-		for (int i = 0, j = nring - 1; i < nring; j = i++) {
-			const double xi = ring[2 * i], yi = ring[2 * i + 1], xj = ring[2 * j], yj = ring[2 * j + 1];
-			if ((yi > y) != (yj > y) && x < (xj - xi) * (y - yi) / (yj - yi) + xi)
-				in = !in;
-		}
-		return in;
-	};
-	// the parent's soundings inside the area, on the parent's own ping x beam frame (so every sounding
-	// keeps its identity), flagged ones carried as mbgetdata carries them (shifted by the flag offset)
+	// the parent's soundings kept, on the parent's own ping x beam frame (so every sounding keeps its
+	// identity), flagged ones carried as mbgetdata carries them (shifted by the flag offset)
 	const int nping = int(p->pingTime.size());
 	int nbeam = 0;
 	for (const auto &s : p->s)
@@ -374,7 +371,7 @@ bool mb3dsdgOpenAreaCloud(void *parentScene, const double *ring, int nring,
 	const size_t nn = size_t(nping) * size_t(nbeam);
 	std::vector<double> lon(nn, NAN), lat(nn, NAN), z(nn, NAN), good;
 	for (const auto &s : p->s) {
-		if (!inside(s.x, s.y))
+		if (!keep(s))
 			continue;
 		const size_t k = size_t(s.ibeam) * size_t(nping) + size_t(s.iping);
 		lon[k] = s.x;
@@ -388,10 +385,10 @@ bool mb3dsdgOpenAreaCloud(void *parentScene, const double *ring, int nring,
 		}
 	}
 	if (good.empty()) {
-		QMessageBox::information(nullptr, "Show point-cloud", "No good sounding of " + p->name + " lies inside this area.");
+		QMessageBox::information(nullptr, "Show point-cloud", QString(none).arg(p->name));
 		return false;
 	}
-	const QString title = p->name + " (area)";
+	const QString title = p->name + " (" + suffix + ")";
 	// the parent waits: its soundings and edits stay, only its pane goes (one 3-D sounding editor at a time)
 	g_cloud = nullptr;
 	if (mb3dsdgIsOpen())
@@ -417,6 +414,76 @@ bool mb3dsdgOpenAreaCloud(void *parentScene, const double *ring, int nring,
 	return false;
 }
 
+bool mb3dsdgOpenAreaCloud(void *parentScene, const double *ring, int nring,
+                          const std::function<void *(const double *xyz, int n, const QString &title)> &makeWindow,
+                          const std::function<void(void *)> &closeWin) {
+	if (!ring || nring < 3)
+		return false;
+	auto inside = [ring, nring](const mb3dsoundings_sounding_struct &s) {   // even-odd rule over the ring
+		bool in = false;
+		for (int i = 0, j = nring - 1; i < nring; j = i++) {
+			const double xi = ring[2 * i], yi = ring[2 * i + 1], xj = ring[2 * j], yj = ring[2 * j + 1];
+			if ((yi > s.y) != (yj > s.y) && s.x < (xj - xi) * (s.y - yi) / (yj - yi) + xi)
+				in = !in;
+		}
+		return in;
+	};
+	return openSubCloud(parentScene, inside, "area", "No good sounding of %1 lies inside this area.",
+	                    makeWindow, closeWin);
+}
+
+// Is `path` one of the swath files of `parentScene`'s cloud? Paths compared as the OS does: separators
+// normalised, and case-blind on Windows.
+static int cloudFileIndex(const Cloud *p, const QString &path) {
+	const QString want = QDir::cleanPath(QDir::fromNativeSeparators(path));
+	for (int i = 0; i < p->files.size(); i++) {
+		const QString have = QDir::cleanPath(QDir::fromNativeSeparators(p->files[i]));
+#ifdef _WIN32
+		if (have.compare(want, Qt::CaseInsensitive) == 0) return i;
+#else
+		if (have == want) return i;
+#endif
+	}
+	return -1;
+}
+
+bool mb3dsdgHasCloudFiles(void *parentScene, const QStringList &files) {
+	const Cloud *p = g_cloud;
+	if (!p || p->scene != parentScene)
+		return false;
+	for (const QString &f : files)
+		if (cloudFileIndex(p, f) >= 0)
+			return true;
+	return false;
+}
+
+bool mb3dsdgOpenFileCloud(void *parentScene, const QStringList &files,
+                          const std::function<void *(const double *xyz, int n, const QString &title)> &makeWindow,
+                          const std::function<void(void *)> &closeWin) {
+	const Cloud *p = g_cloud;
+	if (!p || p->scene != parentScene)
+		return false;
+	std::vector<char> take(size_t(p->files.size()), 0);
+	QStringList names;
+	for (const QString &f : files) {
+		const int i = cloudFileIndex(p, f);
+		if (i < 0 || take[size_t(i)])
+			continue;
+		take[size_t(i)] = 1;
+		names << QFileInfo(f).completeBaseName();
+	}
+	if (names.isEmpty())
+		return false;
+	const std::vector<int> &pf = p->pingFile;
+	auto ofTrack = [&take, &pf](const mb3dsoundings_sounding_struct &s) {
+		return s.iping >= 0 && s.iping < int(pf.size()) && pf[size_t(s.iping)] >= 0 &&
+		       pf[size_t(s.iping)] < int(take.size()) && take[size_t(pf[size_t(s.iping)])];
+	};
+	const QString suffix = names.size() == 1 ? names.front() : QString("%1 tracks").arg(names.size());
+	return openSubCloud(parentScene, ofTrack, suffix, "No good sounding of %1 belongs to this track.",
+	                    makeWindow, closeWin);
+}
+
 bool mb3dsdgAreaOpen() {
 	return g_cloud && g_cloud->parent;
 }
 
@@ -44,9 +44,18 @@ int mb3dsdgEsfFlag(const MbEditHost &host, const QStringList &files, const doubl
 bool mb3dsdgOpenAreaCloud(void *parentScene, const double *ring, int nring,
                           const std::function<void *(const double *xyz, int n, const QString &title)> &makeWindow,
                           const std::function<void(void *)> &closeWin);
+// A navigation track's "Show point-cloud": the same view (the same function underneath), its soundings
+// being those of `parentScene`'s cloud that came from the swath file(s) `files` -- a track, or a group of
+// them. False when nothing opened.
+bool mb3dsdgOpenFileCloud(void *parentScene, const QStringList &files,
+                          const std::function<void *(const double *xyz, int n, const QString &title)> &makeWindow,
+                          const std::function<void(void *)> &closeWin);
+// Does `parentScene`'s swath cloud hold any of `files`? (what offers a track's "Show point-cloud")
+bool mb3dsdgHasCloudFiles(void *parentScene, const QStringList &files);
 // The open 3D Soundings view (mb3dsoundings_window.h): points it draws, good / flagged counts; and View >
 // Show flagged through its menu entry
 bool mb3dsdgCounts(int *drawn, int *good, int *flagged);
+int mb3dsdgPaneButtons();          // shown buttons: bit 0 CUBE filter, bit 1 Gridding, bit 2 Discard; -1 none
 bool mb3dsdgSetShowFlagged(bool on);
 // An area pane is the open one (its parent waiting); its Accept (true) or Discard (false), as its buttons
 bool mb3dsdgAreaOpen();