if getprop("ext.edition") == "ng" then
<your code>
endif;
ui_print("4ext: show_yesno"); # <-- recovery will pause your script and display "yes / no" buttons.
run_program("/sbin/sleep", "2"); # <-- for safety since the above is executed asynchronous
#check the return value by calling:
if getprop("ext.confirm") == "yes" then
<yourcode>
endif;
ui_print("4ext: disable_scrn_update");
# don't forget to enable it again after your yesno binary or graphical installer is finished, by calling:
ui_print("4ext: enable_scrn_update"); #otherwise the recovery will appear to be frozen as it won't update the screen anymore.