diff --git a/app/widget/viewer/viewerdisplay.cpp b/app/widget/viewer/viewerdisplay.cpp
index 9d3ff22f5..b438a4414 100644
--- a/app/widget/viewer/viewerdisplay.cpp
+++ b/app/widget/viewer/viewerdisplay.cpp
@@ -163,10 +163,9 @@ void ViewerDisplayWidget::mousePressEvent(QMouseEvent *event)
     SetMatrixTranslate(mat);
   }
 
+  // get current position in preperation for move event
   if (event->button() == Qt::MiddleButton) {
-    printf("Middle Button Clicked\n");
     position_ = event->pos();
-    printf("x: %d, y:%d\n", position_.x(), position_.y());
     return;
   }
 
@@ -180,18 +179,18 @@ void ViewerDisplayWidget::mousePressEvent(QMouseEvent *event)
 void ViewerDisplayWidget::mouseMoveEvent(QMouseEvent *event)
 {
   if (event->buttons() & Qt::MiddleButton) {
-    printf("Move\n");
     QPointF delta = event->pos() - position_;
+    // scale delta to widget size
     delta.setX(delta.x() / width());
     delta.setY(delta.y() / height());
-    //this->move(this->pos()+new_position);
-    //QPoint new_pos = this->pos() + delta;
+
     QMatrix4x4 mat;
-    //mat.translate(static_cast<float>(new_pos.x()) / width(), static_cast<float>(-1 * new_pos.y()) / height());
-    printf("x: %f, y:%f\n", delta.x(), delta.y());
     mat = GetMatrixTranslate();
+    // Have to invert y axis, possibly because of something in the OpenGL code?
     mat.translate(delta.x(), -1.0f * delta.y());
     SetMatrixTranslate(mat);
+
+    // get new start position
     position_ = event-> pos();
     return;
   }
@@ -278,9 +277,6 @@ void ViewerDisplayWidget::paintGL()
     // Bind retrieved texture
     f->glBindTexture(GL_TEXTURE_2D, texture_.texture());
 
-    //QMatrix4x4 mat;
-    //mat = scale_matrix_ * translate_matrix_ * mat;
-
     // Blit using the color service
     color_service()->ProcessOpenGL(true, GetCompleteMatrix());
 
diff --git a/app/widget/viewer/viewerdisplay.h b/app/widget/viewer/viewerdisplay.h
index 71c804e84..a1f8cec66 100644
--- a/app/widget/viewer/viewerdisplay.h
+++ b/app/widget/viewer/viewerdisplay.h
@@ -66,8 +66,15 @@ public:
 
   virtual ~ViewerDisplayWidget() override;
 
+  /**
+  * @brief Return the translation only matrix.
+  */
   QMatrix4x4 GetMatrixTranslate();
 
+  /**
+   * @brief Return the complete translation and scale matrix
+   * This must be used if you want the entire transformation pipeline (scale and translate).
+   */
   QMatrix4x4 GetCompleteMatrix();
 
   const ViewerSafeMarginInfo& GetSafeMargin() const;
@@ -86,6 +93,10 @@ public slots:
    * Set this if you want the drawing to pass through some sort of transform (most of the time you won't want this).
    */
   void SetMatrixTranslate(const QMatrix4x4& mat);
+ 
+  /**
+  * @brief Set the scale matrix.
+  */
   void SetMatrixZoom(const QMatrix4x4& mat);
 
   /**
@@ -159,10 +170,13 @@ private:
   OpenGLTexture texture_;
 
   /**
-   * @brief Drawing matrix (defaults to identity)
+   * @brief Translation only matrix (defaults to identity).
    */
   QMatrix4x4 translate_matrix_;
 
+  /**
+   * @breif Scale only matrix.
+   */
   QMatrix4x4 scale_matrix_;
 
 #ifdef Q_OS_LINUX
@@ -183,6 +197,9 @@ private:
 
   FramePtr last_loaded_buffer_;
 
+  /**
+   * @brief position of mouse to calculate delta from.
+   */
   QPoint position_;
 
 private slots: