respect timeout==0 -> no timeout

Author: richardsheridan

lib/matplotlib/backends/_backend_tk.py

@@ -359,11 +359,12 @@ def flush_events(self):
 
     def start_event_loop(self, timeout=0):
         # docstring inherited
-        milliseconds = int(1000 * timeout)
-        if milliseconds > 0:
-            self._event_loop_id = self._tkcanvas.after(milliseconds, self.stop_event_loop)
-        else:
-            self._event_loop_id = self._tkcanvas.after_idle(self.stop_event_loop)
+        if timeout > 0:
+            milliseconds = int(1000 * timeout)
+            if milliseconds > 0:
+                self._event_loop_id = self._tkcanvas.after(milliseconds, self.stop_event_loop)
+            else:
+                self._event_loop_id = self._tkcanvas.after_idle(self.stop_event_loop)
         self._master.mainloop()
 
     def stop_event_loop(self):