From a5018c94b83487fbc31b0f908012e1ef5d27e44c Mon Sep 17 00:00:00 2001
From: Vojtech Kral <vojtech@kral.hk>
Date: Tue, 9 Apr 2019 10:55:32 +0200
Subject: [PATCH] GLCanvas3D: Fix an assert in _set_current()

---
 src/slic3r/GUI/GLCanvas3D.cpp | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/src/slic3r/GUI/GLCanvas3D.cpp b/src/slic3r/GUI/GLCanvas3D.cpp
index e97b819a030..9296e816959 100644
--- a/src/slic3r/GUI/GLCanvas3D.cpp
+++ b/src/slic3r/GUI/GLCanvas3D.cpp
@@ -3299,8 +3299,9 @@ bool GLCanvas3D::_init_toolbar()
 
 bool GLCanvas3D::_set_current()
 {
-    if ((m_canvas != nullptr) && (m_context != nullptr))
+    if (_is_shown_on_screen() && (m_context != nullptr)) {
         return m_canvas->SetCurrent(*m_context);
+    }
 
     return false;
 }