Don't exit on no-composote manager, just warn

transparent.py

@@ -31,8 +31,10 @@ class TestWin(Gtk.Window):
         self.screen = self.get_screen()
         self.visual = self.screen.get_rgba_visual()
         if self.visual is None or not self.screen.is_composited():
-            print("ERROR: You do not appear to be running a composite manager")
-            sys.exit(1)
+            print(
+                "WARNING: You do not appear to be running a composite manager"
+                ", transparency not available"
+            )
         else:
             self.set_visual(self.visual)