diff --git a/libs/gtkmm2ext/gtkmm2ext/keyboard.h b/libs/gtkmm2ext/gtkmm2ext/keyboard.h
index 7b206e2ccc..85f034d247 100644
--- a/libs/gtkmm2ext/gtkmm2ext/keyboard.h
+++ b/libs/gtkmm2ext/gtkmm2ext/keyboard.h
@@ -163,6 +163,7 @@ class LIBGTKMM2EXT_API Keyboard : public sigc::trackable, PBD::Stateful
 	static bool is_insert_note_event (GdkEventButton*);
 	static bool is_context_menu_event (GdkEventButton*);
 	static bool is_button2_event (GdkEventButton*);
+	static bool is_momentary_push_event (GdkEventButton*);
 
 	static Keyboard& the_keyboard() { return *_the_keyboard; }
 
@@ -209,6 +210,7 @@ class LIBGTKMM2EXT_API Keyboard : public sigc::trackable, PBD::Stateful
 	static guint     snap_mod;
 	static guint     snap_delta_mod;
 	static guint     button2_modifiers;
+	static guint     momentary_push_modifiers;
 	static Gtk::Window* current_window;
 	static std::string user_keybindings_path;
 	static bool can_save_keybindings;
diff --git a/libs/gtkmm2ext/keyboard.cc b/libs/gtkmm2ext/keyboard.cc
index 83dc8c0cad..58e4e3c31b 100644
--- a/libs/gtkmm2ext/keyboard.cc
+++ b/libs/gtkmm2ext/keyboard.cc
@@ -71,6 +71,7 @@ guint Keyboard::Level4Modifier = GDK_MOD1_MASK; // Alt/Option
 guint Keyboard::CopyModifier = GDK_CONTROL_MASK;      // Control
 guint Keyboard::RangeSelectModifier = GDK_SHIFT_MASK;
 guint Keyboard::button2_modifiers = Keyboard::SecondaryModifier|Keyboard::Level4Modifier;
+guint Keyboard::momentary_push_modifiers = Keyboard::TertiaryModifier;
 
 const char* Keyboard::primary_modifier_name() { return _("Command"); }
 const char* Keyboard::secondary_modifier_name() { return _("Control"); }
@@ -96,6 +97,7 @@ guint Keyboard::Level4Modifier = GDK_MOD4_MASK|GDK_SUPER_MASK; // Mod4/Windows
 guint Keyboard::CopyModifier = GDK_CONTROL_MASK;
 guint Keyboard::RangeSelectModifier = GDK_SHIFT_MASK;
 guint Keyboard::button2_modifiers = 0; /* not used */
+guint Keyboard::momentary_push_modifiers = Keyboard::TertiaryModifier;
 
 const char* Keyboard::primary_modifier_name() { return _("Control"); }
 const char* Keyboard::secondary_modifier_name() { return _("Alt"); }
@@ -546,6 +548,14 @@ Keyboard::is_button2_event (GdkEventButton* ev)
 #endif
 }
 
+bool
+Keyboard::is_momentary_push_event (GdkEventButton* ev)
+{
+	return (is_button2_event(ev)) ||
+		((ev->button == 1) &&
+		 ((ev->state & RelevantModifierKeyMask) == Keyboard::momentary_push_modifiers));
+}
+
 bool
 Keyboard::is_delete_event (GdkEventButton *ev)
 {