diff --git a/gtk2_ardour/editor_group_tabs.cc b/gtk2_ardour/editor_group_tabs.cc
index 6be0b0803c..fdd4954012 100644
--- a/gtk2_ardour/editor_group_tabs.cc
+++ b/gtk2_ardour/editor_group_tabs.cc
@@ -53,12 +53,14 @@ EditorGroupTabs::compute_tabs () const
 		if (g != tab.group) {
 			if (tab.group) {
 				tab.to = y;
+				tab.last_ui_size = (*i)->effective_height ();
 				tabs.push_back (tab);
 			}
 
 			tab.from = y;
 			tab.group = g;
 			tab.colour = (*i)->color ();
+			tab.first_ui_size = (*i)->effective_height ();
 		}
 
 		y += (*i)->effective_height ();
diff --git a/gtk2_ardour/group_tabs.cc b/gtk2_ardour/group_tabs.cc
index 60eed1c7cf..8f82e856a9 100644
--- a/gtk2_ardour/group_tabs.cc
+++ b/gtk2_ardour/group_tabs.cc
@@ -114,16 +114,33 @@ GroupTabs::on_motion_notify_event (GdkEventMotion* ev)
 	}
 
 	if (_drag_from) {
+		
 		double f = _dragging->from + p - _drag_last;
+		
 		if (f < _drag_limit) {
 			f = _drag_limit;
 		}
+
+		double const t = _dragging->to - _dragging->last_ui_size;
+		if (f > t) {
+			f = t;
+		}
+		
 		_dragging->from = f;
+		
 	} else {
+		
 		double t = _dragging->to + p - _drag_last;
+
 		if (t > _drag_limit) {
 			t = _drag_limit;
 		}
+
+		double const f = _dragging->from + _dragging->first_ui_size;
+		if (t < f) {
+			t = f;
+		}
+		
 		_dragging->to = t;
 	}
 
diff --git a/gtk2_ardour/group_tabs.h b/gtk2_ardour/group_tabs.h
index a4ab3304f6..43b00670e0 100644
--- a/gtk2_ardour/group_tabs.h
+++ b/gtk2_ardour/group_tabs.h
@@ -41,6 +41,8 @@ protected:
 		double to;
 		Gdk::Color colour;
 		ARDOUR::RouteGroup* group;
+		double first_ui_size;
+		double last_ui_size;
 	};
 
 private:
diff --git a/gtk2_ardour/mixer_group_tabs.cc b/gtk2_ardour/mixer_group_tabs.cc
index a8fe713aa4..7ab162d3c8 100644
--- a/gtk2_ardour/mixer_group_tabs.cc
+++ b/gtk2_ardour/mixer_group_tabs.cc
@@ -55,12 +55,14 @@ MixerGroupTabs::compute_tabs () const
 		if (g != tab.group) {
 			if (tab.group) {
 				tab.to = x;
+				tab.last_ui_size = (*i)->get_width ();
 				tabs.push_back (tab);
 			}
 
 			tab.from = x;
 			tab.group = g;
 			tab.colour = (*i)->color ();
+			tab.first_ui_size = (*i)->get_width ();
 		}
 
 		x += (*i)->get_width ();