diff --git a/src/libsysprof-gtk/sysprof-chart-layer.c b/src/libsysprof-gtk/sysprof-chart-layer.c
index 6ef3695f..63acbee1 100644
--- a/src/libsysprof-gtk/sysprof-chart-layer.c
+++ b/src/libsysprof-gtk/sysprof-chart-layer.c
@@ -142,3 +142,29 @@ sysprof_chart_layer_snapshot_motion (SysprofChartLayer *self,
   if (SYSPROF_CHART_LAYER_GET_CLASS (self)->snapshot_motion)
     SYSPROF_CHART_LAYER_GET_CLASS (self)->snapshot_motion (self, snapshot, x, y);
 }
+
+/**
+ * sysprof_chart_layer_lookup_item:
+ * @self: a #SysprofChartLayer
+ * @x: the coordinate on the X axis
+ * @y: the coordinate on the Y axis
+ *
+ * Locates an item at `(x,y)`.
+ *
+ * If no item is found at `(x,y)`, then %NULL is returned.
+ *
+ * Returns: (transfer full) (nullable) (type GObject): A #GObject
+ *   if successful; otherwise %NULL.
+ */
+gpointer
+sysprof_chart_layer_lookup_item (SysprofChartLayer *self,
+                                 double             x,
+                                 double             y)
+{
+  g_return_val_if_fail (SYSPROF_IS_CHART_LAYER (self), NULL);
+
+  if (SYSPROF_CHART_LAYER_GET_CLASS (self)->lookup_item)
+    return SYSPROF_CHART_LAYER_GET_CLASS (self)->lookup_item (self, x, y);
+
+  return NULL;
+}
diff --git a/src/libsysprof-gtk/sysprof-chart-layer.h b/src/libsysprof-gtk/sysprof-chart-layer.h
index 5b4c6871..b2720ad4 100644
--- a/src/libsysprof-gtk/sysprof-chart-layer.h
+++ b/src/libsysprof-gtk/sysprof-chart-layer.h
@@ -35,10 +35,13 @@ struct _SysprofChartLayerClass
 {
   GtkWidgetClass parent_class;
 
-  void (*snapshot_motion) (SysprofChartLayer *self,
-                           GtkSnapshot       *snapshot,
-                           double             x,
-                           double             y);
+  gpointer (*lookup_item)     (SysprofChartLayer *self,
+                               double             x,
+                               double             y);
+  void     (*snapshot_motion) (SysprofChartLayer *self,
+                               GtkSnapshot       *snapshot,
+                               double             x,
+                               double             y);
 
   /*< private >*/
   gpointer _reserved[16];
@@ -50,6 +53,10 @@ SYSPROF_AVAILABLE_IN_ALL
 void        sysprof_chart_layer_set_title       (SysprofChartLayer *self,
                                                  const char        *title);
 SYSPROF_AVAILABLE_IN_ALL
+gpointer    sysprof_chart_layer_lookup_item     (SysprofChartLayer *self,
+                                                 double             x,
+                                                 double             y);
+SYSPROF_AVAILABLE_IN_ALL
 void        sysprof_chart_layer_snapshot_motion (SysprofChartLayer *self,
                                                  GtkSnapshot       *snapshot,
                                                  double             x,
diff --git a/src/libsysprof-gtk/sysprof-depth-layer.c b/src/libsysprof-gtk/sysprof-depth-layer.c
index a7e4ff01..5d2cbba6 100644
--- a/src/libsysprof-gtk/sysprof-depth-layer.c
+++ b/src/libsysprof-gtk/sysprof-depth-layer.c
@@ -161,6 +161,22 @@ sysprof_depth_layer_snapshot_motion (SysprofChartLayer *layer,
     gtk_snapshot_append_color (snapshot, &self->hover_color, &rect);
 }
 
+static gpointer
+sysprof_depth_layer_lookup_item (SysprofChartLayer *layer,
+                                 double             x,
+                                 double             y)
+{
+  SysprofDepthLayer *self = (SysprofDepthLayer *)layer;
+  const SysprofXYSeriesValue *v;
+
+  g_assert (SYSPROF_IS_DEPTH_LAYER (self));
+
+  if ((v = sysprof_depth_layer_get_value_at_coord (self, x, y, NULL)))
+    return g_list_model_get_item (sysprof_xy_series_get_model (self->series), v->index);
+
+  return NULL;
+}
+
 static void
 sysprof_depth_layer_dispose (GObject *object)
 {
@@ -238,6 +254,7 @@ sysprof_depth_layer_class_init (SysprofDepthLayerClass *klass)
 
   widget_class->snapshot = sysprof_depth_layer_snapshot;
 
+  chart_layer_class->lookup_item = sysprof_depth_layer_lookup_item;
   chart_layer_class->snapshot_motion = sysprof_depth_layer_snapshot_motion;
 
   properties[PROP_COLOR] =