diff --git a/src/libsysprof-gtk/meson.build b/src/libsysprof-gtk/meson.build
index dae0173e..88aade31 100644
--- a/src/libsysprof-gtk/meson.build
+++ b/src/libsysprof-gtk/meson.build
@@ -3,6 +3,7 @@ libsysprof_gtk_public_sources = [
   'sysprof-mark-chart.c',
   'sysprof-mark-table.c',
   'sysprof-session.c',
+  'sysprof-time-span.c',
   'sysprof-weighted-callgraph-view.c',
 ]
 
@@ -21,6 +22,7 @@ libsysprof_gtk_public_headers = [
   'sysprof-mark-chart.h',
   'sysprof-mark-table.h',
   'sysprof-session.h',
+  'sysprof-time-span.h',
   'sysprof-weighted-callgraph-view.h',
 ]
 
diff --git a/src/libsysprof-gtk/sysprof-gtk.h b/src/libsysprof-gtk/sysprof-gtk.h
index c886f0c3..e0b22302 100644
--- a/src/libsysprof-gtk/sysprof-gtk.h
+++ b/src/libsysprof-gtk/sysprof-gtk.h
@@ -27,6 +27,7 @@ G_BEGIN_DECLS
 # include "sysprof-mark-chart.h"
 # include "sysprof-mark-table.h"
 # include "sysprof-session.h"
+# include "sysprof-time-span.h"
 # include "sysprof-weighted-callgraph-view.h"
 #undef SYSPROF_GTK_INSIDE
 
diff --git a/src/libsysprof-gtk/sysprof-session.c b/src/libsysprof-gtk/sysprof-session.c
index 962982e9..0fe575cc 100644
--- a/src/libsysprof-gtk/sysprof-session.c
+++ b/src/libsysprof-gtk/sysprof-session.c
@@ -25,14 +25,20 @@
 struct _SysprofSession
 {
   GObject          parent_instance;
+
   SysprofDocument *document;
   GtkCustomFilter *filter;
+
+  SysprofTimeSpan  selected_time;
+  SysprofTimeSpan  visible_time;
 };
 
 enum {
   PROP_0,
   PROP_DOCUMENT,
   PROP_FILTER,
+  PROP_SELECTED_TIME,
+  PROP_VISIBLE_TIME,
   N_PROPS
 };
 
@@ -69,6 +75,14 @@ sysprof_session_get_property (GObject    *object,
       g_value_set_object (value, sysprof_session_get_filter (self));
       break;
 
+    case PROP_SELECTED_TIME:
+      g_value_set_boxed (value, sysprof_session_get_selected_time (self));
+      break;
+
+    case PROP_VISIBLE_TIME:
+      g_value_set_boxed (value, sysprof_session_get_visible_time (self));
+      break;
+
     default:
       G_OBJECT_WARN_INVALID_PROPERTY_ID (object, prop_id, pspec);
     }
@@ -112,6 +126,16 @@ sysprof_session_class_init (SysprofSessionClass *klass)
                          GTK_TYPE_FILTER,
                          (G_PARAM_READABLE | G_PARAM_STATIC_STRINGS));
 
+  properties [PROP_SELECTED_TIME] =
+    g_param_spec_boxed ("selected-time", NULL, NULL,
+                        SYSPROF_TYPE_TIME_SPAN,
+                        (G_PARAM_READABLE | G_PARAM_STATIC_STRINGS));
+
+  properties [PROP_VISIBLE_TIME] =
+    g_param_spec_boxed ("visible-time", NULL, NULL,
+                        SYSPROF_TYPE_TIME_SPAN,
+                        (G_PARAM_READABLE | G_PARAM_STATIC_STRINGS));
+
   g_object_class_install_properties (object_class, N_PROPS, properties);
 }
 
@@ -160,3 +184,19 @@ sysprof_session_get_filter (SysprofSession *self)
 
   return GTK_FILTER (self->filter);
 }
+
+const SysprofTimeSpan *
+sysprof_session_get_selected_time (SysprofSession *self)
+{
+  g_return_val_if_fail (SYSPROF_IS_SESSION (self), NULL);
+
+  return &self->selected_time;
+}
+
+const SysprofTimeSpan *
+sysprof_session_get_visible_time (SysprofSession *self)
+{
+  g_return_val_if_fail (SYSPROF_IS_SESSION (self), NULL);
+
+  return &self->visible_time;
+}
diff --git a/src/libsysprof-gtk/sysprof-session.h b/src/libsysprof-gtk/sysprof-session.h
index cf5c705f..a9c27895 100644
--- a/src/libsysprof-gtk/sysprof-session.h
+++ b/src/libsysprof-gtk/sysprof-session.h
@@ -24,6 +24,8 @@
 
 #include <sysprof-analyze.h>
 
+#include "sysprof-time-span.h"
+
 G_BEGIN_DECLS
 
 #define SYSPROF_TYPE_SESSION (sysprof_session_get_type())
@@ -32,10 +34,14 @@ SYSPROF_AVAILABLE_IN_ALL
 G_DECLARE_FINAL_TYPE (SysprofSession, sysprof_session, SYSPROF, SESSION, GObject)
 
 SYSPROF_AVAILABLE_IN_ALL
-SysprofSession  *sysprof_session_new          (SysprofDocument *document);
+SysprofSession        *sysprof_session_new               (SysprofDocument *document);
 SYSPROF_AVAILABLE_IN_ALL
-SysprofDocument *sysprof_session_get_document (SysprofSession  *self);
+SysprofDocument       *sysprof_session_get_document      (SysprofSession  *self);
 SYSPROF_AVAILABLE_IN_ALL
-GtkFilter       *sysprof_session_get_filter   (SysprofSession  *self);
+GtkFilter             *sysprof_session_get_filter        (SysprofSession  *self);
+SYSPROF_AVAILABLE_IN_ALL
+const SysprofTimeSpan *sysprof_session_get_selected_time (SysprofSession  *self);
+SYSPROF_AVAILABLE_IN_ALL
+const SysprofTimeSpan *sysprof_session_get_visible_time  (SysprofSession  *self);
 
 G_END_DECLS
diff --git a/src/libsysprof-gtk/sysprof-time-span.c b/src/libsysprof-gtk/sysprof-time-span.c
new file mode 100644
index 00000000..d690965b
--- /dev/null
+++ b/src/libsysprof-gtk/sysprof-time-span.c
@@ -0,0 +1,37 @@
+/* sysprof-time-span.c
+ *
+ * Copyright 2023 Christian Hergert <chergert@redhat.com>
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ *
+ * SPDX-License-Identifier: GPL-3.0-or-later
+ */
+
+#include "config.h"
+
+#include "sysprof-time-span.h"
+
+G_DEFINE_BOXED_TYPE (SysprofTimeSpan, sysprof_time_span, sysprof_time_span_copy, sysprof_time_span_free)
+
+SysprofTimeSpan *
+sysprof_time_span_copy (const SysprofTimeSpan *self)
+{
+  return g_memdup2 (self, sizeof *self);
+}
+
+void
+sysprof_time_span_free (SysprofTimeSpan *self)
+{
+  g_free (self);
+}
diff --git a/src/libsysprof-gtk/sysprof-time-span.h b/src/libsysprof-gtk/sysprof-time-span.h
new file mode 100644
index 00000000..97d70e8a
--- /dev/null
+++ b/src/libsysprof-gtk/sysprof-time-span.h
@@ -0,0 +1,44 @@
+/* sysprof-time-span.h
+ *
+ * Copyright 2023 Christian Hergert <chergert@redhat.com>
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ *
+ * SPDX-License-Identifier: GPL-3.0-or-later
+ */
+
+#pragma once
+
+#include <glib-object.h>
+
+#include <sysprof-capture.h>
+
+G_BEGIN_DECLS
+
+#define SYSPROF_TYPE_TIME_SPAN (sysprof_time_span_get_type())
+
+typedef struct _SysprofTimeSpan
+{
+  gint64 begin_nsec;
+  gint64 end_nsec;
+} SysprofTimeSpan;
+
+SYSPROF_AVAILABLE_IN_ALL
+GType            sysprof_time_span_get_type (void) G_GNUC_CONST;
+SYSPROF_AVAILABLE_IN_ALL
+SysprofTimeSpan *sysprof_time_span_copy     (const SysprofTimeSpan *self);
+SYSPROF_AVAILABLE_IN_ALL
+void             sysprof_time_span_free     (SysprofTimeSpan       *self);
+
+G_END_DECLS