diff --git a/gtk2_ardour/plugin_ui.cc b/gtk2_ardour/plugin_ui.cc
index ca619e2f31..ed1b8305e6 100644
--- a/gtk2_ardour/plugin_ui.cc
+++ b/gtk2_ardour/plugin_ui.cc
@@ -51,6 +51,7 @@
 #include "ardour/lv2_plugin.h"
 #include "ardour/plugin.h"
 #include "ardour/plugin_insert.h"
+#include "ardour/region_fx_plugin.h"
 #include "ardour/session.h"
 #include "lv2_plugin_ui.h"
 
@@ -85,7 +86,7 @@ extern VST3PluginUI* create_mac_vst3_gui (std::shared_ptr<ARDOUR::PlugInsertBase
 #include "ardour_window.h"
 #include "gui_thread.h"
 #include "keyboard.h"
-#include "latency_gui.h"
+#include "timectl_gui.h"
 #include "new_plugin_preset_dialog.h"
 #include "plugin_dspload_ui.h"
 #include "plugin_eq_gui.h"
@@ -537,6 +538,8 @@ PlugUIBase::PlugUIBase (std::shared_ptr<PlugInsertBase> pib)
 	, cpuload_expander (_("CPU Profile"))
 	, latency_gui (0)
 	, latency_dialog (0)
+	, tailtime_gui (0)
+	, tailtime_dialog (0)
 	, eqgui (0)
 	, stats_gui (0)
 	, preset_gui (0)
@@ -555,6 +558,7 @@ PlugUIBase::PlugUIBase (std::shared_ptr<PlugInsertBase> pib)
 	set_tooltip (_pin_management_button, _("Show Plugin Pin Management Dialog"));
 	set_tooltip (_bypass_button, _("Disable signal processing by the plugin"));
 	set_tooltip (_latency_button, _("Edit Plugin Delay/Latency Compensation"));
+	set_tooltip (_tailtime_button, _("Edit Plugin tail time"));
 	_no_load_preset = 0;
 
 	update_preset_list ();
@@ -565,6 +569,11 @@ PlugUIBase::PlugUIBase (std::shared_ptr<PlugInsertBase> pib)
 	_latency_button.signal_clicked.connect (sigc::mem_fun (*this, &PlugUIBase::latency_button_clicked));
 	set_latency_label ();
 
+	_tailtime_button.set_icon (ArdourIcon::TailTimeClock);
+	_tailtime_button.add_elements (ArdourButton::Text);
+	_tailtime_button.signal_clicked.connect (sigc::mem_fun (*this, &PlugUIBase::tailtime_button_clicked));
+	set_tailtime_label ();
+
 	_add_button.set_name ("generic button");
 	_add_button.set_icon (ArdourIcon::PsetAdd);
 	_add_button.signal_clicked.connect (sigc::mem_fun (*this, &PlugUIBase::add_plugin_setting));
@@ -636,6 +645,11 @@ PlugUIBase::PlugUIBase (std::shared_ptr<PlugInsertBase> pib)
 		_pi->LatencyChanged.connect (*this, invalidator (*this), boost::bind (&PlugUIBase::set_latency_label, this), gui_context ());
 		automation_state_changed ();
 	}
+
+	shared_ptr<TailTime> tt = std::dynamic_pointer_cast<ARDOUR::TailTime> (_pib);
+	if (tt) {
+		tt->TailTimeChanged.connect (*this, invalidator (*this), boost::bind (&PlugUIBase::set_tailtime_label, this), gui_context ());
+	}
 }
 
 PlugUIBase::~PlugUIBase ()
@@ -645,6 +659,8 @@ PlugUIBase::~PlugUIBase ()
 	delete preset_gui;
 	delete latency_gui;
 	delete latency_dialog;
+	delete tailtime_gui;
+	delete tailtime_dialog;
 	delete preset_dialog;
 
 	delete _focus_out_image;
@@ -696,6 +712,9 @@ PlugUIBase::add_common_widgets (Gtk::HBox* b, bool with_focus)
 		b->pack_end (_pin_management_button, false, false);
 		b->pack_start (_latency_button, false, false, 4);
 	}
+	else if (std::dynamic_pointer_cast<ARDOUR::RegionFxPlugin> (_pib)) {
+		b->pack_start (_tailtime_button, false, false, 4);
+	}
 }
 
 void
@@ -709,13 +728,26 @@ PlugUIBase::set_latency_label ()
 
 	_latency_button.set_text (samples_as_time_string (l, sr, true));
 }
+void
+
+PlugUIBase::set_tailtime_label ()
+{
+	auto rfx = std::dynamic_pointer_cast<ARDOUR::RegionFxPlugin> (_pib); /* may be NULL */
+	if (!rfx) {
+		return;
+	}
+	samplecnt_t const l  = rfx->effective_tailtime ();
+	float const       sr = rfx->session ().sample_rate ();
+
+	_tailtime_button.set_text (samples_as_time_string (l, sr, true));
+}
 
 void
 PlugUIBase::latency_button_clicked ()
 {
 	assert (_pi);
 	if (!latency_gui) {
-		latency_gui    = new LatencyGUI (*(_pi.get ()), _pi->session ().sample_rate (), _pi->session ().get_block_size ());
+		latency_gui    = new TimeCtlGUI (*(_pi.get ()), _pi->session ().sample_rate (), _pi->session ().get_block_size ());
 		latency_dialog = new ArdourWindow (_("Edit Latency"));
 		/* use both keep-above and transient for to try cover as many
 		   different WM's as possible.
@@ -732,6 +764,29 @@ PlugUIBase::latency_button_clicked ()
 	latency_dialog->show_all ();
 }
 
+void
+PlugUIBase::tailtime_button_clicked ()
+{
+	auto rfx = std::dynamic_pointer_cast<ARDOUR::RegionFxPlugin> (_pib); /* may be NULL */
+	assert (rfx);
+	if (!tailtime_gui) {
+		tailtime_gui    = new TimeCtlGUI (*dynamic_cast<TailTime*>(rfx.get()), rfx->session ().sample_rate (), rfx->session ().get_block_size ());
+		tailtime_dialog = new ArdourWindow (_("Edit Tail Time"));
+		/* use both keep-above and transient for to try cover as many
+		   different WM's as possible.
+		*/
+		tailtime_dialog->set_keep_above (true);
+		Window* win = dynamic_cast<Window*> (_bypass_button.get_toplevel ());
+		if (win) {
+			tailtime_dialog->set_transient_for (*win);
+		}
+		tailtime_dialog->add (*tailtime_gui);
+	}
+
+	tailtime_gui->refresh ();
+	tailtime_dialog->show_all ();
+}
+
 void
 PlugUIBase::processor_active_changed (std::weak_ptr<Processor> weak_p)
 {
diff --git a/gtk2_ardour/plugin_ui.h b/gtk2_ardour/plugin_ui.h
index 2963a6f7a9..d4a38259da 100644
--- a/gtk2_ardour/plugin_ui.h
+++ b/gtk2_ardour/plugin_ui.h
@@ -81,7 +81,7 @@ namespace ArdourWidgets {
 	class FastMeter;
 }
 
-class LatencyGUI;
+class TimeCtlGUI;
 class ArdourWindow;
 class PluginEqGui;
 class PluginLoadStatsGui;
@@ -110,6 +110,7 @@ public:
 	void update_preset ();
 
 	void latency_button_clicked ();
+	void tailtime_button_clicked ();
 
 	virtual bool on_window_show(const std::string& /*title*/) { return true; }
 	virtual void on_window_hide() {}
@@ -157,6 +158,8 @@ protected:
 	Gtk::Expander cpuload_expander;
 	/** a button which, when clicked, opens the latency GUI */
 	ArdourWidgets::ArdourButton _latency_button;
+	/** a button which, when clicked, opens the tailtime GUI */
+	ArdourWidgets::ArdourButton _tailtime_button;
 	/** a button which sets all controls' automation setting to Manual */
 	ArdourWidgets::ArdourButton automation_manual_all_button;
 	/** a button which sets all controls' automation setting to Play */
@@ -169,9 +172,13 @@ protected:
 	ArdourWidgets::ArdourButton automation_latch_all_button;
 
 	void set_latency_label ();
-	LatencyGUI* latency_gui;
+	TimeCtlGUI*   latency_gui;
 	ArdourWindow* latency_dialog;
 
+	void set_tailtime_label ();
+	TimeCtlGUI*   tailtime_gui;
+	ArdourWindow* tailtime_dialog;
+
 	PluginEqGui* eqgui;
 	PluginLoadStatsGui* stats_gui;
 	PluginPresetsUI* preset_gui;
diff --git a/gtk2_ardour/port_insert_ui.cc b/gtk2_ardour/port_insert_ui.cc
index 0b22f83d2a..7c88924da7 100644
--- a/gtk2_ardour/port_insert_ui.cc
+++ b/gtk2_ardour/port_insert_ui.cc
@@ -35,7 +35,7 @@
 
 #include "context_menu_helper.h"
 #include "gui_thread.h"
-#include "latency_gui.h"
+#include "timectl_gui.h"
 #include "port_insert_ui.h"
 #include "timers.h"
 #include "utils.h"
@@ -282,7 +282,7 @@ PortInsertUI::edit_latency_button_clicked ()
 {
 	assert (_pi);
 	if (!_latency_gui) {
-		_latency_gui    = new LatencyGUI (*(_pi.get ()), _pi->session ().sample_rate (), _pi->session ().get_block_size ());
+		_latency_gui    = new TimeCtlGUI (*(_pi.get ()), _pi->session ().sample_rate (), _pi->session ().get_block_size ());
 		_latency_dialog = new ArdourWindow (_("Edit Latency"));
 		/* use both keep-above and transient for to try cover as many
 		   different WM's as possible.
diff --git a/gtk2_ardour/port_insert_ui.h b/gtk2_ardour/port_insert_ui.h
index 6538b7015b..94f4188419 100644
--- a/gtk2_ardour/port_insert_ui.h
+++ b/gtk2_ardour/port_insert_ui.h
@@ -31,7 +31,7 @@ namespace ARDOUR
 	class PortInsert;
 }
 
-class LatencyGUI;
+class TimeCtlGUI;
 class MTDM;
 
 class PortInsertUI : public Gtk::VBox
@@ -78,7 +78,7 @@ private:
 	Gtk::HBox  _latency_hbox;
 
 	Gtk::Window*  _parent;
-	LatencyGUI*   _latency_gui;
+	TimeCtlGUI*   _latency_gui;
 	ArdourWindow* _latency_dialog;
 
 	sigc::connection _latency_timeout;
diff --git a/gtk2_ardour/latency_gui.cc b/gtk2_ardour/timectl_gui.cc
similarity index 59%
rename from gtk2_ardour/latency_gui.cc
rename to gtk2_ardour/timectl_gui.cc
index e3c8d12dc2..f5f3ae6af1 100644
--- a/gtk2_ardour/latency_gui.cc
+++ b/gtk2_ardour/timectl_gui.cc
@@ -29,10 +29,12 @@
 #include "pbd/unwind.h"
 
 #include "ardour/latent.h"
+#include "ardour/rc_configuration.h"
+#include "ardour/tailtime.h"
 
 #include "gtkmm2ext/utils.h"
 
-#include "latency_gui.h"
+#include "timectl_gui.h"
 #include "utils.h"
 
 #include "pbd/i18n.h"
@@ -50,46 +52,66 @@ static const gchar *_unit_strings[] = {
 	0
 };
 
-std::vector<std::string> LatencyGUI::unit_strings;
+std::vector<std::string> TimeCtlGUI::unit_strings;
 
 std::string
-LatencyBarController::get_label (double&)
+TimeCtlBarController::get_label (double&)
 {
 	return ARDOUR_UI_UTILS::samples_as_time_string (
-			_latency_gui->adjustment.get_value(), _latency_gui->sample_rate, true);
+			_timectl_gui->adjustment.get_value(), _timectl_gui->sample_rate, true);
 }
 
 void
-LatencyGUIControllable::set_value (double v, PBD::Controllable::GroupControlDisposition group_override)
+TimeCtlGUIControllable::set_value (double v, PBD::Controllable::GroupControlDisposition group_override)
 {
-	_latency_gui->adjustment.set_value (v);
+	_timectl_gui->adjustment.set_value (v);
 }
 
 double
-LatencyGUIControllable::get_value () const
+TimeCtlGUIControllable::get_value () const
 {
-	return _latency_gui->adjustment.get_value ();
+	return _timectl_gui->adjustment.get_value ();
 }
 double
-LatencyGUIControllable::lower() const
+TimeCtlGUIControllable::lower() const
 {
-	return _latency_gui->adjustment.get_lower ();
+	return _timectl_gui->adjustment.get_lower ();
 }
 
 double
-LatencyGUIControllable::upper() const
+TimeCtlGUIControllable::upper() const
 {
-	return _latency_gui->adjustment.get_upper ();
+	return _timectl_gui->adjustment.get_upper ();
 }
 
-LatencyGUI::LatencyGUI (Latent& l, samplepos_t sr, samplepos_t psz)
-	: _latent (l)
+TimeCtlGUI::TimeCtlGUI (Latent& l, samplepos_t sr, samplepos_t psz)
+	: _latent (&l)
+	, _tailtime (0)
 	, sample_rate (sr)
 	, period_size (psz)
 	, _ignore_change (false)
 	, adjustment (0, 0.0, sample_rate, 1.0, sample_rate / 1000.0f) /* max 1 second, step by samples, page by msecs */
 	, bc (adjustment, this)
 	, reset_button (_("Reset"))
+{
+	init ();
+}
+
+TimeCtlGUI::TimeCtlGUI (TailTime& t, samplepos_t sr, samplepos_t psz)
+	: _latent (0)
+	, _tailtime (&t)
+	, sample_rate (sr)
+	, period_size (psz)
+	, _ignore_change (false)
+	, adjustment (0, 0.0, 20 * sample_rate, sample_rate / 1000.f, 1.0, sample_rate / 2.0f) /* max 20 second, step by msec, page by 0.5 sec */
+	, bc (adjustment, this)
+	, reset_button (_("Reset"))
+{
+	init ();
+}
+
+void
+TimeCtlGUI::init ()
 {
 	Widget* w;
 
@@ -116,17 +138,21 @@ LatencyGUI::LatencyGUI (Latent& l, samplepos_t sr, samplepos_t psz)
 	hbox2.pack_start (plus_button);
 	hbox2.pack_start (units_combo, true, true);
 
-	minus_button.signal_clicked().connect (sigc::bind (sigc::mem_fun (*this, &LatencyGUI::change_latency_from_button), -1));
-	plus_button.signal_clicked().connect (sigc::bind (sigc::mem_fun (*this, &LatencyGUI::change_latency_from_button), 1));
-	reset_button.signal_clicked().connect (sigc::mem_fun (*this, &LatencyGUI::reset));
+	minus_button.signal_clicked().connect (sigc::bind (sigc::mem_fun (*this, &TimeCtlGUI::change_from_button), -1));
+	plus_button.signal_clicked().connect (sigc::bind (sigc::mem_fun (*this, &TimeCtlGUI::change_from_button), 1));
+	reset_button.signal_clicked().connect (sigc::mem_fun (*this, &TimeCtlGUI::reset));
 
 	/* Limit value to adjustment range (max = sample_rate).
 	 * Otherwise if the signal_latency() is larger than the adjustment's max,
-	 * LatencyGUI::finish() would set the adjustment's max value as custom-latency.
+	 * TimeCtlGUI::finish() would set the adjustment's max value as custom-latency.
 	 */
-	adjustment.set_value (std::min (sample_rate, _latent.signal_latency ()));
+	if (_latent) {
+		adjustment.set_value (std::min (sample_rate, _latent->signal_latency ()));
+	} else if (_tailtime) {
+		adjustment.set_value (std::min (sample_rate, _tailtime->signal_tailtime ()));
+	}
 
-	adjustment.signal_value_changed().connect (sigc::mem_fun (*this, &LatencyGUI::finish));
+	adjustment.signal_value_changed().connect (sigc::mem_fun (*this, &TimeCtlGUI::finish));
 
 	bc.set_size_request (-1, 25);
 	bc.set_name (X_("ProcessorControlSlider"));
@@ -137,32 +163,46 @@ LatencyGUI::LatencyGUI (Latent& l, samplepos_t sr, samplepos_t psz)
 }
 
 void
-LatencyGUI::finish ()
+TimeCtlGUI::finish ()
 {
 	if (_ignore_change) {
 		return;
 	}
 	samplepos_t new_value = (samplepos_t) adjustment.get_value();
-	_latent.set_user_latency (new_value);
+	if (_latent) {
+		_latent->set_user_latency (new_value);
+	} else if (_tailtime) {
+		_tailtime->set_user_tailtime (new_value);
+	}
 }
 
 void
-LatencyGUI::reset ()
+TimeCtlGUI::reset ()
 {
-	_latent.unset_user_latency ();
-	PBD::Unwinder<bool> uw (_ignore_change, true);
-	adjustment.set_value (std::min (sample_rate, _latent.signal_latency ()));
+	if (_latent) {
+		_latent->unset_user_latency ();
+		PBD::Unwinder<bool> uw (_ignore_change, true);
+		adjustment.set_value (std::min (sample_rate, _latent->signal_latency ()));
+	} else if (_tailtime) {
+		_tailtime->unset_user_tailtime ();
+		PBD::Unwinder<bool> uw (_ignore_change, true);
+		adjustment.set_value (std::min<samplecnt_t> (Config->get_max_tail_samples (), _tailtime->signal_tailtime ()));
+	}
 }
 
 void
-LatencyGUI::refresh ()
+TimeCtlGUI::refresh ()
 {
 	PBD::Unwinder<bool> uw (_ignore_change, true);
-	adjustment.set_value (std::min (sample_rate, _latent.effective_latency ()));
+	if (_latent) {
+		adjustment.set_value (std::min (sample_rate, _latent->effective_latency ()));
+	} else if (_tailtime) {
+		adjustment.set_value (std::min<samplecnt_t> (Config->get_max_tail_samples (),_tailtime->effective_tailtime ()));
+	}
 }
 
 void
-LatencyGUI::change_latency_from_button (int dir)
+TimeCtlGUI::change_from_button (int dir)
 {
 	std::string unitstr = units_combo.get_active_text();
 	double shift = 0.0;
diff --git a/gtk2_ardour/latency_gui.h b/gtk2_ardour/timectl_gui.h
similarity index 69%
rename from gtk2_ardour/latency_gui.h
rename to gtk2_ardour/timectl_gui.h
index 838e01d848..b20d253ac0 100644
--- a/gtk2_ardour/latency_gui.h
+++ b/gtk2_ardour/timectl_gui.h
@@ -2,7 +2,7 @@
  * Copyright (C) 2007-2017 Paul Davis <paul@linuxaudiosystems.com>
  * Copyright (C) 2009 Carl Hetherington <carl@carlh.net>
  * Copyright (C) 2009 David Robillard <d@drobilla.net>
- * Copyright (C) 2017-2019 Robin Gareus <robin@gareus.org>
+ * Copyright (C) 2017-2024 Robin Gareus <robin@gareus.org>
  *
  * 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
@@ -19,8 +19,8 @@
  * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
  */
 
-#ifndef __gtk2_ardour_latency_gui_h__
-#define __gtk2_ardour_latency_gui_h__
+#ifndef __gtk2_ardour_timectl_gui_h__
+#define __gtk2_ardour_timectl_gui_h__
 
 #include <vector>
 #include <string>
@@ -38,16 +38,17 @@
 
 namespace ARDOUR {
 	class Latent;
+	class TailTime;
 }
 
-class LatencyGUI;
+class TimeCtlGUI;
 
-class LatencyGUIControllable : public PBD::Controllable
+class TimeCtlGUIControllable : public PBD::Controllable
 {
 public:
-	LatencyGUIControllable (LatencyGUI* g)
+	TimeCtlGUIControllable (TimeCtlGUI* g)
 		: PBD::Controllable ("ignoreMe")
-		, _latency_gui (g)
+		, _timectl_gui (g)
 	{}
 
 	void set_value (double v, PBD::Controllable::GroupControlDisposition group_override);
@@ -62,44 +63,48 @@ public:
 	}
 
 private:
-	LatencyGUI* _latency_gui;
+	TimeCtlGUI* _timectl_gui;
 };
 
-class LatencyBarController : public ArdourWidgets::BarController
+class TimeCtlBarController : public ArdourWidgets::BarController
 {
 public:
-	LatencyBarController (Gtk::Adjustment& adj, LatencyGUI* g)
-		: BarController (adj, std::shared_ptr<PBD::Controllable> (new LatencyGUIControllable (g)))
-		, _latency_gui (g)
+	TimeCtlBarController (Gtk::Adjustment& adj, TimeCtlGUI* g)
+		: BarController (adj, std::shared_ptr<PBD::Controllable> (new TimeCtlGUIControllable (g)))
+		, _timectl_gui (g)
 	{
 		set_digits (0);
 	}
 
 private:
-	LatencyGUI* _latency_gui;
+	TimeCtlGUI* _timectl_gui;
 
 	std::string get_label (double&);
 };
 
-class LatencyGUI : public Gtk::VBox
+class TimeCtlGUI : public Gtk::VBox
 {
 public:
-	LatencyGUI (ARDOUR::Latent&, samplepos_t sample_rate, samplepos_t period_size);
-	~LatencyGUI() { }
+	TimeCtlGUI (ARDOUR::Latent&, samplepos_t sample_rate, samplepos_t period_size);
+	TimeCtlGUI (ARDOUR::TailTime&, samplepos_t sample_rate, samplepos_t period_size);
+	~TimeCtlGUI() { }
 
 	void refresh ();
 
 private:
+	void init ();
 	void reset ();
 	void finish ();
 
-	ARDOUR::Latent& _latent;
+	ARDOUR::Latent*   _latent;
+	ARDOUR::TailTime* _tailtime;
+
 	samplepos_t sample_rate;
 	samplepos_t period_size;
 
 	bool _ignore_change;
 	Gtk::Adjustment adjustment;
-	LatencyBarController bc;
+	TimeCtlBarController bc;
 	Gtk::HBox hbox1;
 	Gtk::HBox hbox2;
 	Gtk::HButtonBox hbbox;
@@ -108,12 +113,12 @@ private:
 	Gtk::Button reset_button;
 	Gtk::ComboBoxText units_combo;
 
-	void change_latency_from_button (int dir);
+	void change_from_button (int dir);
 
-	friend class LatencyBarController;
-	friend class LatencyGUIControllable;
+	friend class TimeCtlBarController;
+	friend class TimeCtlGUIControllable;
 
 	static std::vector<std::string> unit_strings;
 };
 
-#endif /* __gtk2_ardour_latency_gui_h__ */
+#endif /* __gtk2_ardour_timectl_gui_h__ */
diff --git a/gtk2_ardour/wscript b/gtk2_ardour/wscript
index d1e0f94274..e16141a3f1 100644
--- a/gtk2_ardour/wscript
+++ b/gtk2_ardour/wscript
@@ -139,7 +139,6 @@ gtk2_ardour_sources = [
         'hit.cc',
         'keyboard.cc',
         'keyeditor.cc',
-        'latency_gui.cc',
         'led.cc',
         'level_meter.cc',
         'library_download_dialog.cc',
@@ -301,6 +300,7 @@ gtk2_ardour_sources = [
         'time_fx_dialog.cc',
         'time_info_box.cc',
         'time_selection.cc',
+        'timectl_gui.cc',
         'timers.cc',
         'track_record_axis.cc',
         'track_selection.cc',