Bugfix in invalidate code: PromptSession was invalidating the UI continuously.

jonathanslenders · jonathanslenders · commit a800ea4ce020 · 2020-03-04T17:59:00.000+01:00
When the refresh interval is 0, which is the default in `PromptSession`, don't
run a refresh loop. This significantly reduces CPU usage when idle.
diff --git a/prompt_toolkit/application/application.py b/prompt_toolkit/application/application.py
@@ -527,7 +527,7 @@ def _start_auto_refresh_task(self) -> None:
         Start a while/true loop in the background for automatic invalidation of
         the UI.
         """
-        if self.refresh_interval is not None:
+        if self.refresh_interval not in (None, 0):
             refresh_interval = self.refresh_interval
 
             async def auto_refresh() -> None:
