[pitivi/1.0] effects: Hide GL effects until they are well supported

[Alexandru Băluț <alexbalut src gnome org>]

commit 3cebe474163536b40d2179857bd62faac8144cd8
Author: Alexandru Băluț <alexandru balut gmail com>
Date:   Tue May 14 21:40:42 2019 +0200

    effects: Hide GL effects until they are well supported
    
    Fixes #2320

 pitivi/effects.py | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)
---
diff --git a/pitivi/effects.py b/pitivi/effects.py
index 8bcd9e5a..74835b14 100644
--- a/pitivi/effects.py
+++ b/pitivi/effects.py
@@ -287,8 +287,11 @@ class EffectsManager(Loggable):
         self.gl_effects = [element_factory.get_name()
                            for element_factory in gl_element_factories]
         if self.gl_effects:
-            thread = threading.Thread(target=self._check_gleffects)
-            thread.start()
+            if "gleffects" in os.environ.get("PITIVI_UNSTABLE_FEATURES", ""):
+                thread = threading.Thread(target=self._check_gleffects)
+                thread.start()
+            else:
+                HIDDEN_EFFECTS.extend(self.gl_effects)
 
     def _check_gleffects(self):
         try: