test `output_gallery_component` as output

app.py

@@ -98,7 +98,13 @@ with gr.Blocks() as demo:
                     value='Submit', variant='primary', scale=0)
         with gr.Column():
             output_gallery_component = gr.Gallery(
-                object_fit="contain", height="auto", label='Generated image')
+                columns=[1],
+                rows=[2],
+                selected_index=0,
+                preview=True,
+                object_fit="contain",
+                height="auto",
+                label='Generated image')
 
     submit_button_component.click(
         fn=process,