diff --git a/src/slic3r/GUI/GLCanvas3D.cpp b/src/slic3r/GUI/GLCanvas3D.cpp
index 7a0ca3e8ff..92078a8b9d 100644
--- a/src/slic3r/GUI/GLCanvas3D.cpp
+++ b/src/slic3r/GUI/GLCanvas3D.cpp
@@ -5114,6 +5114,7 @@ void GLCanvas3D::bind_event_handlers()
         m_canvas->Bind(wxEVT_SIZE, &GLCanvas3D::on_size, this);
         m_canvas->Bind(wxEVT_IDLE, &GLCanvas3D::on_idle, this);
         m_canvas->Bind(wxEVT_CHAR, &GLCanvas3D::on_char, this);
+        m_canvas->Bind(wxEVT_KEY_UP, &GLCanvas3D::on_key_up, this);
         m_canvas->Bind(wxEVT_MOUSEWHEEL, &GLCanvas3D::on_mouse_wheel, this);
         m_canvas->Bind(wxEVT_TIMER, &GLCanvas3D::on_timer, this);
         m_canvas->Bind(wxEVT_LEFT_DOWN, &GLCanvas3D::on_mouse, this);
@@ -5139,6 +5140,7 @@ void GLCanvas3D::unbind_event_handlers()
         m_canvas->Unbind(wxEVT_SIZE, &GLCanvas3D::on_size, this);
         m_canvas->Unbind(wxEVT_IDLE, &GLCanvas3D::on_idle, this);
         m_canvas->Unbind(wxEVT_CHAR, &GLCanvas3D::on_char, this);
+        m_canvas->Unbind(wxEVT_KEY_UP, &GLCanvas3D::on_key_up, this);
         m_canvas->Unbind(wxEVT_MOUSEWHEEL, &GLCanvas3D::on_mouse_wheel, this);
         m_canvas->Unbind(wxEVT_TIMER, &GLCanvas3D::on_timer, this);
         m_canvas->Unbind(wxEVT_LEFT_DOWN, &GLCanvas3D::on_mouse, this);
@@ -5182,7 +5184,12 @@ void GLCanvas3D::on_char(wxKeyEvent& evt)
         switch (keyCode) {
         case 'a':
         case 'A':
-        case WXK_CONTROL_A: post_event(SimpleEvent(EVT_GLCANVAS_SELECT_ALL)); break;
+        case WXK_CONTROL_A:
+            if (m_gizmos.get_current_type() == Gizmos::SlaSupports) // Sla gizmo selects all support points
+                m_gizmos.mouse_event(5);
+            else
+                post_event(SimpleEvent(EVT_GLCANVAS_SELECT_ALL));
+        break;
 #ifdef __APPLE__
         case WXK_BACK: // the low cost Apple solutions are not equipped with a Delete key, use Backspace instead.
 #else /* __APPLE__ */
@@ -5240,6 +5247,18 @@ void GLCanvas3D::on_char(wxKeyEvent& evt)
     }
 }
 
+void GLCanvas3D::on_key_up(wxKeyEvent& evt)
+{
+    // see include/wx/defs.h enum wxKeyCode
+    int keyCode = evt.GetKeyCode();
+
+    // shift has been just released - SLA gizmo might want to close rectangular selection:
+    if (m_gizmos.get_current_type() == Gizmos::SlaSupports && keyCode == WXK_SHIFT) {
+        m_gizmos.mouse_event(2);
+        m_dirty = true;
+    }
+}
+
 void GLCanvas3D::on_mouse_wheel(wxMouseEvent& evt)
 {
     // Ignore the wheel events if the middle button is pressed.
@@ -5586,6 +5605,7 @@ void GLCanvas3D::on_mouse(wxMouseEvent& evt)
     else if (evt.Dragging() && m_gizmos.get_current_type() == Gizmos::SlaSupports && evt.ShiftDown())
     {
         m_gizmos.mouse_event(3, Vec2d(pos(0), pos(1)), evt.ShiftDown());
+        m_dirty = true;
     }
     else if (evt.Dragging() && !gizmos_overlay_contains_mouse)
     {
diff --git a/src/slic3r/GUI/GLCanvas3D.hpp b/src/slic3r/GUI/GLCanvas3D.hpp
index 6fd4584a6f..db630988ce 100644
--- a/src/slic3r/GUI/GLCanvas3D.hpp
+++ b/src/slic3r/GUI/GLCanvas3D.hpp
@@ -789,7 +789,7 @@ private:
         void set_flattening_data(const ModelObject* model_object);
 
         void set_sla_support_data(ModelObject* model_object, const GLCanvas3D::Selection& selection);
-        void mouse_event(int action, const Vec2d& mouse_position, bool shift_down);
+        void mouse_event(int action, const Vec2d& mouse_position = Vec2d::Zero(), bool shift_down = false);
         void delete_current_grabber(bool delete_all = false);
 
         void render_current_gizmo(const Selection& selection) const;
@@ -1050,6 +1050,7 @@ public:
     void on_size(wxSizeEvent& evt);
     void on_idle(wxIdleEvent& evt);
     void on_char(wxKeyEvent& evt);
+    void on_key_up(wxKeyEvent& evt);
     void on_mouse_wheel(wxMouseEvent& evt);
     void on_timer(wxTimerEvent& evt);
     void on_mouse(wxMouseEvent& evt);
diff --git a/src/slic3r/GUI/GLGizmo.cpp b/src/slic3r/GUI/GLGizmo.cpp
index f752e7d943..e58eb8500e 100644
--- a/src/slic3r/GUI/GLGizmo.cpp
+++ b/src/slic3r/GUI/GLGizmo.cpp
@@ -1847,12 +1847,17 @@ void GLGizmoSlaSupports::render_selection_rectangle() const
     ::glOrtho(0.f, m_canvas_width, m_canvas_height, 0.f, -1.f, 1.f); // set projection matrix so that world coords = window coords
 
     // render the selection  rectangle (window coordinates):
+    ::glPushAttrib(GL_ENABLE_BIT);
+    ::glLineStipple(4, 0xAAAA);
+    ::glEnable(GL_LINE_STIPPLE);
+
     ::glBegin(GL_LINE_LOOP);
     ::glVertex3f((GLfloat)m_selection_rectangle_start_corner(0), (GLfloat)m_selection_rectangle_start_corner(1), (GLfloat)0.5f);
     ::glVertex3f((GLfloat)m_selection_rectangle_end_corner(0), (GLfloat)m_selection_rectangle_start_corner(1), (GLfloat)0.5f);
     ::glVertex3f((GLfloat)m_selection_rectangle_end_corner(0), (GLfloat)m_selection_rectangle_end_corner(1), (GLfloat)0.5f);
     ::glVertex3f((GLfloat)m_selection_rectangle_start_corner(0), (GLfloat)m_selection_rectangle_end_corner(1), (GLfloat)0.5f);
     ::glEnd();
+    ::glPopAttrib();
 
     ::glPopMatrix();                // restore former projection matrix
     ::glMatrixMode(GL_MODELVIEW);
@@ -2035,10 +2040,8 @@ void GLGizmoSlaSupports::mouse_event(int action, const Vec2d& mouse_position, bo
     }
 
     // dragging the selection rectangle:
-    if (action == 3 && m_selection_rectangle_active) {
+    if (action == 3 && m_selection_rectangle_active)
         m_selection_rectangle_end_corner = mouse_position;
-        m_parent.render();
-    }
 
     // mouse up without selection rectangle - place point on the mesh:
     if (action == 2 && !m_selection_rectangle_active) {
@@ -2096,6 +2099,15 @@ void GLGizmoSlaSupports::mouse_event(int action, const Vec2d& mouse_position, bo
         }
         m_selection_rectangle_active = false;
     }
+
+    if (action == 4) {
+        // shift has been released
+    }
+
+    if (action == 5) {
+        // ctrl+A : select all
+        std::cout << "select all..." << std::endl;
+    }
 }
 
 void GLGizmoSlaSupports::delete_current_point(bool delete_all)