From cf1b25dfc84d18397d984ffd22e161ab44908b6a Mon Sep 17 00:00:00 2001
From: Alessandro Ranellucci <aar@cpan.org>
Date: Thu, 19 Jun 2014 10:27:23 +0200
Subject: [PATCH] Bugfix: prevent the "bad drawable" error when showing the
 OpenGL canvas. #2015 #2099

---
 lib/Slic3r/GUI/PreviewCanvas.pm | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/lib/Slic3r/GUI/PreviewCanvas.pm b/lib/Slic3r/GUI/PreviewCanvas.pm
index d6d61de2f0..522a0507cd 100644
--- a/lib/Slic3r/GUI/PreviewCanvas.pm
+++ b/lib/Slic3r/GUI/PreviewCanvas.pm
@@ -382,8 +382,10 @@ sub InitGL {
  
 sub Render {
     my ($self, $dc) = @_;
- 
-    return unless $self->GetContext;
+    
+    # prevent calling SetCurrent() when window is not shown yet
+    return unless $self->IsShownOnScreen;
+    return unless my $context = $self->GetContext;
     $self->SetCurrent($self->GetContext);
     $self->InitGL;