+

+screen countdown(timer_jump, time=5): # I set a default reaction time of 5 seconds

+    timer time repeat False action [ Hide('countdown'), Jump(timer_jump) ]

+    bar value AnimatedValue(0, time, time, time) at alpha_dissolve # assuming you're using the alpha_dissolve transform from the wiki

+

+label start:

+    "start test"

+    show screen countdown("jump_label") # This uses the default time of 5.

+#    show screen countdown("jump_label", 10) # This line, uncommented, will take 10 rather than 5 seconds.

+    menu:

+        "Choice 1":

+            hide screen countdown

+        "Choice 2":

+            hide screen countdown

+

+label jump_label: