Fix SVG rendering error in def update_background (matplotlib#30490)

Check if saving before updating blitting background

---------

Co-authored-by: AASMA GUPTA <aasmagupta@Aasmas-Mac.local>
Co-authored-by: Tim Hoffmann <2836374+timhoffm@users.noreply.github.com>

Author: 3 people

lib/matplotlib/widgets.py

@@ -2172,6 +2172,8 @@ def update_background(self, event):
         # `release` can call a draw event even when `ignore` is True.
         if not self.useblit:
             return
+        if self.canvas.is_saving():
+            return  # saving does not use blitting
         # Make sure that widget artists don't get accidentally included in the
         # background, by re-rendering the background if needed (and then
         # re-re-rendering the canvas with the visible widget artists).