Hi Sara,
here you have to capture the selected value into your field (GV_FORWARD_AGENT). in this component every time do_prepare_output will call so you can capture the selected value over there otherwise if you want to capture only when you click on button then you have to write the code in to your button event..
or you can write the code in your mailbody.htm..
example code:
id is your input id along with _ ex ( _input)
lv_cmpid = me->component_id.
CONCATENATE lv_cmpid id INTO lv_idt.
me->gv_input_field = htmlb_event->if_htmlb_data~event_id.
data_input ?= cl_htmlb_manager=>get_data(
request = runtime->server->request
name = 'inputField'
id = lv_idt ).
IF data_input IS NOT INITIAL.
GV_FORWARD_AGENT= data_input->value.
ENDIF.
Try this and let me know..
Regards,
Srinivas.