diff --git a/ActionManager.cpp b/ActionManager.cpp
index b53283e..3fb5342 100644
--- a/ActionManager.cpp
+++ b/ActionManager.cpp
@@ -69,6 +69,9 @@ void captureMixerSession(tinyxml2::XMLDocument *doc, std::string node, std::stri
         delete thumbnail;
     }
 
+    // save session attributes
+    sessionNode->SetAttribute("activationThreshold", se->activationThreshold());
+
     // save all sources using source visitor
     SessionVisitor sv(doc, sessionNode);
     for (auto iter = se->begin(); iter != se->end(); ++iter, sv.setRoot(sessionNode) )
diff --git a/CMakeLists.txt b/CMakeLists.txt
index 9b85f73..0ed142d 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -413,6 +413,7 @@ set(VMIX_RSC_FILES
     ./rsc/mesh/shadow_perspective.ply
     ./rsc/mesh/point.ply
     ./rsc/mesh/square_point.ply
+    ./rsc/mesh/triangle_point.ply
     ./rsc/mesh/icon_video.ply
     ./rsc/mesh/icon_image.ply
     ./rsc/mesh/icon_render.ply
diff --git a/Mixer.cpp b/Mixer.cpp
index 660cd35..6477e3b 100644
--- a/Mixer.cpp
+++ b/Mixer.cpp
@@ -1334,7 +1334,6 @@ void Mixer::restore(tinyxml2::XMLElement *sessionNode)
     //
     // source lists
     //
-
     // sessionsources contains list of ids of all sources currently in the session (before loading)
     SourceIdList session_sources = session_->getIdList();
 //    for( auto it = sessionsources.begin(); it != sessionsources.end(); it++)
diff --git a/MixingView.cpp b/MixingView.cpp
index e4be714..19a5c68 100644
--- a/MixingView.cpp
+++ b/MixingView.cpp
@@ -48,7 +48,7 @@ uint textureMixingQuadratic();
 
 
 
-MixingView::MixingView() : View(MIXING), limbo_scale_(MIXING_LIMBO_SCALE)
+MixingView::MixingView() : View(MIXING), limbo_scale_(MIXING_MIN_THRESHOLD)
 {
     scene.root()->scale_ = glm::vec3(MIXING_DEFAULT_SCALE, MIXING_DEFAULT_SCALE, 1.0f);
     scene.root()->translation_ = glm::vec3(0.0f, 0.0f, 0.0f);
@@ -62,10 +62,30 @@ MixingView::MixingView() : View(MIXING), limbo_scale_(MIXING_LIMBO_SCALE)
         restoreSettings();
 
     // Mixing scene background
-    Mesh *tmp = new Mesh("mesh/disk.ply");
-    tmp->scale_ = glm::vec3(limbo_scale_, limbo_scale_, 1.f);
-    tmp->shader()->color = glm::vec4( COLOR_LIMBO_CIRCLE, 0.6f );
-    scene.bg()->attach(tmp);
+    limbo_ = new Mesh("mesh/disk.ply");
+    limbo_->scale_ = glm::vec3(limbo_scale_, limbo_scale_, 1.f);
+    limbo_->shader()->color = glm::vec4( COLOR_LIMBO_CIRCLE, 1.f );
+    scene.bg()->attach(limbo_);
+
+    // interactive limbo scaling slider
+    limbo_slider_root_ = new Group;
+    limbo_slider_root_->translation_ = glm::vec3(0.0f, limbo_scale_, 0.f);
+    scene.bg()->attach(limbo_slider_root_);
+    limbo_slider_ = new Disk();
+    limbo_slider_->translation_ = glm::vec3(0.f, -0.01f, 0.f);
+    limbo_slider_->scale_ = glm::vec3(0.1f, 0.1f, 1.f);
+    limbo_slider_->color = glm::vec4( COLOR_LIMBO_CIRCLE, 1.f );
+    limbo_slider_root_->attach(limbo_slider_);
+    limbo_up_ = new Mesh("mesh/triangle_point.ply");
+    limbo_up_->scale_ = glm::vec3(0.8f, 0.8f, 1.f);
+    limbo_up_->shader()->color = glm::vec4( COLOR_CIRCLE_OVER, 0.01f );
+    limbo_slider_root_->attach(limbo_up_);
+    limbo_down_ = new Mesh("mesh/triangle_point.ply");
+    limbo_down_->translation_ = glm::vec3(0.f, -0.02f, 0.f);
+    limbo_down_->scale_ = glm::vec3(0.8f, 0.8f, 1.f);
+    limbo_down_->rotation_ = glm::vec3(0.f, 0.f, M_PI);
+    limbo_down_->shader()->color = glm::vec4( COLOR_CIRCLE_OVER, 0.01f );
+    limbo_slider_root_->attach(limbo_down_);
 
     mixingCircle_ = new Mesh("mesh/disk.ply");
     mixingCircle_->shader()->color = glm::vec4( 1.f, 1.f, 1.f, 1.f );
@@ -77,8 +97,8 @@ MixingView::MixingView() : View(MIXING), limbo_scale_(MIXING_LIMBO_SCALE)
 
     // Mixing scene foreground
 
-    // button frame
-    tmp = new Mesh("mesh/disk.ply");
+    // button frame (non interactive; no picking detected on Mesh)
+    Mesh *tmp = new Mesh("mesh/disk.ply");
     tmp->scale_ = glm::vec3(0.033f, 0.033f, 1.f);
     tmp->translation_ = glm::vec3(0.f, 1.f, 0.f);
     tmp->shader()->color = glm::vec4( COLOR_CIRCLE, 0.9f );
@@ -118,10 +138,10 @@ MixingView::MixingView() : View(MIXING), limbo_scale_(MIXING_LIMBO_SCALE)
     slider_root_->attach(tmp);
 
 
-    stashCircle_ = new Disk();
-    stashCircle_->scale_ = glm::vec3(0.5f, 0.5f, 1.f);
-    stashCircle_->translation_ = glm::vec3(2.f, -1.0f, 0.f);
-    stashCircle_->color = glm::vec4( COLOR_STASH_CIRCLE, 0.6f );
+//    stashCircle_ = new Disk();
+//    stashCircle_->scale_ = glm::vec3(0.5f, 0.5f, 1.f);
+//    stashCircle_->translation_ = glm::vec3(2.f, -1.0f, 0.f);
+//    stashCircle_->color = glm::vec4( COLOR_STASH_CIRCLE, 0.6f );
 //    scene.bg()->attach(stashCircle_);
 
 }
@@ -293,6 +313,13 @@ void MixingView::update(float dt)
     // for mixing, this means restore position of the fading slider
     if (View::need_deep_update_ > 0) {
 
+        //
+        // Set limbo scale according to session
+        //
+        const float p = CLAMP(Mixer::manager().session()->activationThreshold(), MIXING_MIN_THRESHOLD, MIXING_MAX_THRESHOLD);
+        limbo_slider_root_->translation_.y = p;
+        limbo_->scale_ = glm::vec3(p, p, 1.f);
+
         //
         // Set slider to match the actual fading of the session
         //
@@ -312,8 +339,8 @@ void MixingView::update(float dt)
     }
 
     // the current view is the mixing view
-    if (Mixer::manager().view() == this )
-    {
+    if (Mixer::manager().view() == this ){
+
         //
         // Set session fading to match the slider angle (during animation)
         //
@@ -449,6 +476,22 @@ View::Cursor MixingView::grab (Source *s, glm::vec2 from, glm::vec2 to, std::pai
             info  << "Global opacity " << 100 - int(Mixer::manager().session()->fading() * 100.0) << " %";
             return Cursor(Cursor_Hand, info.str() );
         }
+        else if (pick.first == limbo_slider_) {
+
+            // move slider scaling limbo area
+            const float p = CLAMP(gl_Position_to.y, MIXING_MIN_THRESHOLD, MIXING_MAX_THRESHOLD);
+            limbo_slider_root_->translation_.y = p;
+            limbo_->scale_ = glm::vec3(p, p, 1.f);
+            Mixer::manager().session()->setActivationThreshold(p);
+
+            // color change of arrow indicators
+            limbo_up_->shader()->color = glm::vec4( COLOR_CIRCLE_OVER, p < MIXING_MAX_THRESHOLD ? 0.15f : 0.01f );
+            limbo_down_->shader()->color = glm::vec4( COLOR_CIRCLE_OVER, p > MIXING_MIN_THRESHOLD ? 0.15f : 0.01f );
+
+            std::ostringstream info;
+            info << ICON_FA_SNOWFLAKE " Deactivation limit";
+            return Cursor(Cursor_Hand, info.str() );
+        }
 
         // nothing to do
         return Cursor();
@@ -532,6 +575,16 @@ View::Cursor MixingView::over (glm::vec2 pos)
     else
         slider_->color = glm::vec4( COLOR_CIRCLE, 0.9f );
 
+    if ( pick.first == limbo_slider_ ) {
+        limbo_up_->shader()->color = glm::vec4( COLOR_CIRCLE_OVER, limbo_slider_root_->translation_.y < MIXING_MAX_THRESHOLD ? 0.1f : 0.01f );
+        limbo_down_->shader()->color = glm::vec4( COLOR_CIRCLE_OVER, limbo_slider_root_->translation_.y > MIXING_MIN_THRESHOLD ? 0.1f : 0.01f );
+        ret.type = Cursor_Hand;
+    }
+    else {
+        limbo_up_->shader()->color = glm::vec4( COLOR_CIRCLE_OVER, 0.01f );
+        limbo_down_->shader()->color = glm::vec4( COLOR_CIRCLE_OVER, 0.01f );
+    }
+
 
     return ret;
 }
diff --git a/MixingView.h b/MixingView.h
index 74ba8c3..55687aa 100644
--- a/MixingView.h
+++ b/MixingView.h
@@ -26,7 +26,6 @@ public:
     void arrow (glm::vec2) override;
 
     void setAlpha (Source *s);
-    inline float limboScale() { return limbo_scale_; }
 
 private:
     void updateSelectionOverlay() override;
@@ -37,9 +36,13 @@ private:
     Disk *slider_;
     Disk *button_white_;
     Disk *button_black_;
-    Disk *stashCircle_;
+//    Disk *stashCircle_;
     Mesh *mixingCircle_;
     Mesh *circle_;
+    Mesh *limbo_;
+    Group *limbo_slider_root_;
+    Mesh *limbo_up_, *limbo_down_;
+    Disk *limbo_slider_;
 };
 
 
diff --git a/Session.cpp b/Session.cpp
index 58ad33e..40b501a 100644
--- a/Session.cpp
+++ b/Session.cpp
@@ -37,7 +37,8 @@ SessionNote::SessionNote(const std::string &t, bool l, int s): label(std::to_str
 {
 }
 
-Session::Session() : active_(true), filename_(""), failedSource_(nullptr), fading_target_(0.f), thumbnail_(nullptr)
+Session::Session() : active_(true), activation_threshold_(MIXING_MIN_THRESHOLD),
+    filename_(""), failedSource_(nullptr), fading_target_(0.f), thumbnail_(nullptr)
 {
     config_[View::RENDERING] = new Group;
     config_[View::RENDERING]->scale_ = glm::vec3(0.f);
@@ -131,6 +132,7 @@ void Session::update(float dt)
             // render the source
             (*it)->render();
             // update the source
+            (*it)->setActive( (*it)->mix_distance() < activation_threshold_);
             (*it)->update(dt);
         }
     }
diff --git a/Session.h b/Session.h
index 4c2ca47..93c18fc 100644
--- a/Session.h
+++ b/Session.h
@@ -101,6 +101,10 @@ public:
     void setFading (float f, bool forcenow = false);
     inline float fading () const { return fading_target_; }
 
+    // activation threshold for source (mixing distance)
+    inline void setActivationThreshold(float t) { activation_threshold_ = t; }
+    inline float activationThreshold() const { return activation_threshold_;}
+
     // configuration for group nodes of views
     inline Group *config (View::Mode m) const { return config_.at(m); }
 
@@ -147,6 +151,7 @@ public:
 
 protected:
     bool active_;
+    float activation_threshold_;
     RenderView render_;
     std::string filename_;
     Source *failedSource_;
diff --git a/SessionCreator.cpp b/SessionCreator.cpp
index 71f8ec6..7f62f14 100644
--- a/SessionCreator.cpp
+++ b/SessionCreator.cpp
@@ -291,8 +291,18 @@ void SessionLoader::load(XMLElement *sessionNode)
         return;
     }
 
-    if (sessionNode != nullptr && session_ != nullptr) {
+    if (sessionNode != nullptr && session_ != nullptr)
+    {
+        //
+        // session attributes
+        //
+        float t = MIXING_MIN_THRESHOLD;
+        sessionNode->QueryFloatAttribute("activationThreshold", &t);
+        session_->setActivationThreshold(t);
 
+        //
+        // source lists
+        //
         XMLElement* sourceNode = sessionNode->FirstChildElement("Source");
         for( ; sourceNode ; sourceNode = sourceNode->NextSiblingElement())
         {
diff --git a/SessionVisitor.cpp b/SessionVisitor.cpp
index 044d175..213e44f 100644
--- a/SessionVisitor.cpp
+++ b/SessionVisitor.cpp
@@ -70,6 +70,9 @@ bool SessionVisitor::saveSession(const std::string& filename, Session *session)
         // source visitor
         (*iter)->accept(sv);
 
+    // save session attributes
+    sessionNode->SetAttribute("activationThreshold", session->activationThreshold());
+
     // save the thumbnail
     FrameBufferImage *thumbnail = session->thumbnail();
     if (thumbnail != nullptr && thumbnail->width > 0 && thumbnail->height > 0) {
diff --git a/Source.cpp b/Source.cpp
index 644a5dd..d6da88d 100644
--- a/Source.cpp
+++ b/Source.cpp
@@ -519,6 +519,10 @@ void Source::attach(FrameBuffer *renderbuffer)
 
 void Source::setActive (bool on)
 {
+    // request update
+    need_update_ |= active_ != on;
+
+    // activate
     active_ = on;
 
     // do not disactivate if a clone depends on it
@@ -571,6 +575,11 @@ void Source::setDepth(float d)
     touch();
 }
 
+float Source::mix_distance()
+{
+    return glm::length( glm::vec2(groups_[View::MIXING]->translation_) );
+}
+
 float Source::alpha() const
 {
     return blendingShader()->color.a;
@@ -578,6 +587,7 @@ float Source::alpha() const
 
 void Source::setAlpha(float a)
 {
+    a = CLAMP(a, 0.f, 1.f);
     glm::vec2 dist = glm::vec2(groups_[View::MIXING]->translation_);
     glm::vec2 step = glm::normalize(glm::vec2(1.f, 1.f));// step in diagonal by default
 
@@ -587,10 +597,10 @@ void Source::setAlpha(float a)
 
     // converge to reduce the difference of alpha
     // using dichotomic algorithm
-    float delta = sin_quad_(dist.x, dist.y) - CLAMP(a, 0.f, 1.f);
+    float delta = sin_quad_(dist.x, dist.y) - a;
     while ( glm::abs(delta) > DELTA_ALPHA ){
         dist += step * (delta / 2.f);
-        delta = sin_quad_(dist.x, dist.y) - CLAMP(a, 0.f, 1.f);
+        delta = sin_quad_(dist.x, dist.y) - a;
     }
 
     // apply new mixing coordinates
@@ -613,12 +623,8 @@ void Source::update(float dt)
         // use the sinusoidal transfer function
         blendingshader_->color = glm::vec4(1.f, 1.f, 1.f, sin_quad_( dist.x, dist.y ));
         mixingshader_->color = blendingshader_->color;
-
-        // CHANGE update status based on limbo
-        bool a = glm::length(dist) < MIXING_LIMBO_SCALE;
-        setActive( a );
         // adjust scale of mixing icon : smaller if not active
-        groups_[View::MIXING]->scale_ = glm::vec3(MIXING_ICON_SCALE) - ( a ? glm::vec3(0.f, 0.f, 0.f) : glm::vec3(0.03f, 0.03f, 0.f) );
+        groups_[View::MIXING]->scale_ = glm::vec3(MIXING_ICON_SCALE) - ( active_ ? glm::vec3(0.f, 0.f, 0.f) : glm::vec3(0.03f, 0.03f, 0.f) );
 
         // MODIFY geometry based on GEOMETRY node
         groups_[View::RENDERING]->translation_ = groups_[View::GEOMETRY]->translation_;
diff --git a/Source.h b/Source.h
index 1fb1a03..f257e20 100644
--- a/Source.h
+++ b/Source.h
@@ -170,6 +170,7 @@ public:
     void  setDepth (float d);
 
     // operations on alpha
+    float mix_distance ();
     float alpha () const;
     void  setAlpha (float a);
 
diff --git a/defines.h b/defines.h
index d73c8af..bf8e554 100644
--- a/defines.h
+++ b/defines.h
@@ -34,7 +34,8 @@
 #define MIXING_DEFAULT_SCALE 2.4f
 #define MIXING_MIN_SCALE 0.8f
 #define MIXING_MAX_SCALE 7.0f
-#define MIXING_LIMBO_SCALE 1.3f
+#define MIXING_MIN_THRESHOLD 1.3f
+#define MIXING_MAX_THRESHOLD 1.9f
 #define MIXING_ICON_SCALE 0.15f, 0.15f, 1.f
 #define GEOMETRY_DEFAULT_SCALE 1.4f
 #define GEOMETRY_MIN_SCALE 0.4f
@@ -102,7 +103,7 @@
 #define COLOR_CIRCLE 0.75f, 0.2f, 0.75f
 #define COLOR_CIRCLE_OVER 0.8f, 0.8f, 0.8f
 #define COLOR_MIXING_GROUP 0.f, 0.95f, 0.2f
-#define COLOR_LIMBO_CIRCLE 0.16f, 0.16f, 0.16f
+#define COLOR_LIMBO_CIRCLE 0.173f, 0.173f, 0.173f
 #define COLOR_SLIDER_CIRCLE 0.11f, 0.11f, 0.11f
 #define COLOR_STASH_CIRCLE 0.06f, 0.06f, 0.06f
 
diff --git a/rsc/mesh/triangle_point.ply b/rsc/mesh/triangle_point.ply
new file mode 100644
index 0000000..48b78cf
--- /dev/null
+++ b/rsc/mesh/triangle_point.ply
@@ -0,0 +1,143 @@
+ply
+format ascii 1.0
+comment Created by Blender 2.93.3 - www.blender.org
+element vertex 54
+property float x
+property float y
+property float z
+property float nx
+property float ny
+property float nz
+element face 76
+property list uchar uint vertex_indices
+end_header
+0.057448 0.004658 0.000000 0.000000 0.000000 1.000000
+0.057742 0.002329 0.000000 0.000000 0.000000 1.000000
+0.058884 0.002939 0.000000 0.000000 0.000000 1.000000
+-0.004658 0.057448 0.000000 0.000000 0.000000 1.000000
+-0.002329 0.057742 0.000000 0.000000 0.000000 1.000000
+-0.003079 0.058745 0.000000 0.000000 0.000000 1.000000
+0.000139 -0.000883 0.000000 -0.000000 -0.000000 1.000000
+-0.028728 0.002329 0.000000 -0.000000 -0.000000 1.000000
+-0.028724 -0.002329 0.000000 -0.000000 -0.000000 1.000000
+0.002329 0.028729 0.000000 -0.000000 0.000000 1.000000
+-0.002329 0.028729 0.000000 -0.000000 0.000000 1.000000
+0.028724 -0.002329 0.000000 0.000000 0.000000 1.000000
+0.028728 0.002329 0.000000 0.000000 0.000000 1.000000
+-0.059486 0.001456 0.000000 0.000000 0.000000 1.000000
+-0.058759 0.000728 0.000000 0.000000 0.000000 1.000000
+-0.058884 0.002939 0.000000 0.000000 0.000000 1.000000
+-0.059486 -0.000000 0.000000 0.000000 0.000000 1.000000
+-0.059486 -0.001456 0.000000 0.000000 0.000000 1.000000
+-0.058884 -0.003218 0.000000 0.000000 0.000000 1.000000
+-0.058759 -0.000728 0.000000 0.000000 0.000000 1.000000
+-0.001456 0.059486 0.000000 0.000000 0.000000 1.000000
+-0.000728 0.058759 0.000000 0.000000 0.000000 1.000000
+-0.000000 0.059486 0.000000 0.000000 0.000000 1.000000
+-0.000000 0.058032 0.000000 0.000000 0.000000 1.000000
+0.002329 0.057742 0.000000 0.000000 0.000000 1.000000
+0.000728 0.058759 0.000000 0.000000 0.000000 1.000000
+0.059486 0.001456 0.000000 0.000000 -0.000000 1.000000
+0.058759 0.000728 0.000000 0.000000 -0.000000 1.000000
+0.059486 0.000000 0.000000 0.000000 -0.000000 1.000000
+0.058032 0.000000 0.000000 0.000000 -0.000000 1.000000
+0.057742 -0.002329 0.000000 0.000000 -0.000000 1.000000
+0.058759 -0.000728 0.000000 0.000000 -0.000000 1.000000
+-0.058032 0.000000 0.000000 0.000000 0.000000 1.000000
+-0.057742 -0.002329 0.000000 0.000000 0.000000 1.000000
+-0.057742 0.002329 0.000000 0.000000 0.000000 1.000000
+-0.015529 0.015529 0.000000 -0.000000 0.000000 1.000000
+-0.017855 0.044250 0.000000 0.000000 -0.000000 1.000000
+0.015529 0.015529 0.000000 0.000000 0.000000 1.000000
+0.004658 0.057448 0.000000 -0.000000 0.000000 1.000000
+-0.000000 0.057453 0.000000 -0.000000 0.000000 1.000000
+0.031053 0.031053 0.000000 0.000000 -0.000000 1.000000
+0.044250 0.017855 0.000000 0.000000 -0.000000 1.000000
+0.057453 0.000000 0.000000 0.000000 0.000000 1.000000
+0.057448 -0.004658 0.000000 0.000000 -0.000000 1.000000
+0.017855 0.044250 0.000000 0.000000 0.000000 1.000000
+-0.031053 0.031053 0.000000 0.000000 -0.000000 1.000000
+-0.044250 0.017855 0.000000 -0.000000 0.000000 1.000000
+-0.057448 0.004658 0.000000 -0.000000 0.000000 1.000000
+-0.057453 0.000000 0.000000 0.000000 0.000000 1.000000
+-0.057448 -0.004658 0.000000 0.000000 0.000000 1.000000
+0.058884 -0.003218 0.000000 0.000000 0.000000 1.000000
+0.059486 -0.001456 0.000000 0.000000 0.000000 1.000000
+0.003079 0.058745 0.000000 0.000000 0.000000 1.000000
+0.001456 0.059486 0.000000 0.000000 0.000000 1.000000
+3 0 1 2
+3 3 4 5
+3 6 7 8
+3 6 9 10
+3 6 11 12
+3 13 14 15
+3 13 16 14
+3 17 18 19
+3 20 21 22
+3 23 24 25
+3 26 27 28
+3 29 30 31
+3 32 33 34
+3 6 35 7
+3 3 36 10
+3 6 37 9
+3 38 24 39
+3 40 37 41
+3 0 42 1
+3 1 30 29
+3 1 42 30
+3 42 43 30
+3 41 12 0
+3 41 37 12
+3 37 6 12
+3 39 4 3
+3 39 24 4
+3 24 23 4
+3 9 44 38
+3 9 37 44
+3 37 40 44
+3 10 35 6
+3 10 36 35
+3 36 45 35
+3 7 46 47
+3 7 35 46
+3 35 45 46
+3 34 48 47
+3 34 33 48
+3 33 49 48
+3 31 50 51
+3 31 30 50
+3 30 43 50
+3 28 31 51
+3 28 27 31
+3 27 29 31
+3 25 52 53
+3 25 24 52
+3 24 38 52
+3 22 25 53
+3 22 21 25
+3 21 23 25
+3 19 33 32
+3 19 18 33
+3 18 49 33
+3 14 19 32
+3 14 16 19
+3 16 17 19
+3 15 34 47
+3 15 14 34
+3 14 32 34
+3 12 42 0
+3 12 11 42
+3 11 43 42
+3 10 39 3
+3 10 9 39
+3 9 38 39
+3 8 48 49
+3 8 7 48
+3 7 47 48
+3 5 21 20
+3 5 4 21
+3 4 23 21
+3 2 27 26
+3 2 1 27
+3 1 29 27