diff --git a/lib/QGLSurface.cc b/lib/QGLSurface.cc
index 7abdcd3..3c588ec 100644
--- a/lib/QGLSurface.cc
+++ b/lib/QGLSurface.cc
@@ -40,6 +40,19 @@ QGLSurface::QGLSurface(QWidget *parent, qt_sink_c_impl *block)
 	this->setSizePolicy(QSizePolicy::Expanding, QSizePolicy::Expanding);
 }
 
+
+void
+QGLSurface::hideEvent(QHideEvent *he)
+{
+	this->d_block->cb_visibility(this->isVisible());
+}
+
+void
+QGLSurface::showEvent(QShowEvent *he)
+{
+	this->d_block->cb_visibility(this->isVisible());
+}
+
 void
 QGLSurface::paintEvent(QPaintEvent *pe)
 {
diff --git a/lib/QGLSurface.h b/lib/QGLSurface.h
index 65afd8a..a10b2a1 100644
--- a/lib/QGLSurface.h
+++ b/lib/QGLSurface.h
@@ -38,6 +38,8 @@ namespace gr {
       QThread *d_gui_thread;
 
      protected:
+      void hideEvent(QHideEvent *he);
+      void showEvent(QShowEvent *he);
       void paintEvent(QPaintEvent *pe);
       void resizeEvent(QResizeEvent *re);
       void keyPressEvent(QKeyEvent *ke);