Fixed infinite loop in OpenGL BackgroundRectangle.get_color() (#3732)

Co-authored-by: Francisco Manríquez Novoa <[email protected]>

Author: camburd2

manim/mobject/opengl/opengl_vectorized_mobject.py

@@ -324,6 +324,7 @@ def match_style(self, vmobject, recurse=True):
         vmobject_style = vmobject.get_style()
         if config.renderer == RendererType.OPENGL:
             vmobject_style["stroke_width"] = vmobject_style["stroke_width"][0][0]
+            vmobject_style["fill_opacity"] = self.get_fill_opacity()
         self.set_style(**vmobject_style, recurse=False)
         if recurse:
             # Does its best to match up submobject lists, and
@@ -405,7 +406,7 @@ def get_stroke_opacity(self):
         return self.get_stroke_opacities()[0]
 
     def get_color(self):
-        if self.has_stroke():
+        if not self.has_fill():
             return self.get_stroke_color()
         return self.get_fill_color()