Hi Bubai,
when you click on end button do_prepare_event will get trigger clear the custom values in that method.
like this..
clear : me->cutomvalue.
if you want to know the end,call,save button functionality then go to crmcmp_ic_frame.
CRMCMP_IC_FRAME/HiddenView
component CRMCMP_IC_FRAME to check END button functionality.In this view put the break point in event
EH_ONFORWARDCALL and check it.
In this component you can also check
Pages with Flow Logic
header_jscripts.js for all button code.
want to know more about this go through this links..
End Button Functionality in SAP CRM, IC Agent role | SCN
CRM Web UI - how to disable REJECT and END in IC header
Restrict AutoSave on End Button in IC-Agent Role
Thanks & Regards,
Srinivask.