clarify set_one_shot

panda/src/display/graphicsOutput.I

@@ -238,10 +238,22 @@ is_valid() const {
 //     Function: GraphicsOutput::set_one_shot
 //       Access: Published
 //  Description: Changes the current setting of the one-shot flag.
-//               When this is true, the GraphicsOutput will
-//               automatically detach its texture (if it has one) and
-//               remove itself from the GraphicsEngine after it
-//               renders the next frame.
+//               When this is true, the GraphicsOutput will render one
+//               frame and then automatically set itself inactive.
+//               This is particularly useful for buffers that are
+//               created for the purposes of render-to-texture, for
+//               static textures that don't need to be continually
+//               re-rendered once they have been rendered the first
+//               time.
+//
+//               Setting the buffer inactive is not the same thing as
+//               destroying it.  You are still responsible for passing
+//               this buffer to GraphicsEngine::remove_window() when
+//               you no longer need the texture, in order to clean up
+//               fully.  (However, you should not call remove_window()
+//               on this buffer while the texture is still needed,
+//               because depending on the render-to-texture mechanism
+//               in use, this may invalidate the texture contents.)
 ////////////////////////////////////////////////////////////////////
 INLINE void GraphicsOutput::
 set_one_shot(bool one_shot) {