Update doc strings.

batgrl/gadgets/animation.py

@@ -274,7 +274,7 @@ def on_size(self):
 
     @property
     def is_transparent(self) -> bool:
-        """If false, `alpha` and alpha channels are ignored."""
+        """Whether gadget is transparent."""
         return self._is_transparent
 
     @is_transparent.setter

batgrl/gadgets/graphic_field.py

@@ -38,10 +38,9 @@ class GraphicParticleField(Gadget):
     r"""
     A graphic particle field.
 
-    A particle field specializes in rendering many single "pixel" children by
-    setting particle positions, colors, and alphas. (Note that alpha channel
-    of particle colors and particle alphas are independent and both control
-    particle transparency.) This is more efficient than rendering many 1x1 gadgets.
+    A particle field specializes in rendering many single "pixel" children with just
+    particle positions and  colors. This is more efficient than rendering many 1x1
+    gadgets.
 
     Parameters
     ----------

batgrl/gadgets/parallax.py

@@ -260,7 +260,7 @@ def on_size(self):
 
     @property
     def is_transparent(self) -> bool:
-        """If false, `alpha` and alpha channels are ignored."""
+        """Whether gadget is transparent."""
         return self._is_transparent
 
     @is_transparent.setter