How to focus a record in forms

Hi

I have multi rows form and I want to highlight current record in block. So when I move cursor to each row it will change color. How to do this I try use this code:

declare
cur_block varchar2(40) := :System.Cursor_Block;
cur_itm varchar2(40);
begin
cur_itm := Get_Block_Property( 'my_block',FIRST_ITEM );
-- focus
while( cur_itm is not null ) loop
Set_Item_Instance_Property( cur_itm, CURRENT_RECORD, VISUAL_ATTRIBUTE, 'hhh');
cur_itm := Get_Item_Property( cur_itm, NEXTITEM);
end loop;
---
How to retrive previus record to set it visual_atribute to normal??

I solve problem by using:

post-record and when-new-instance-record triggers.
But How to retrive amout of record fetch by query?

Now code is:
PRE-FORM
intializing global.my_var := 0;

-- in my_block trigger level
POST-RECORD
:GLOBAL.my_var := Get_Block_Property( 'my_block', CURRENT_RECORD);

WHEN-NEW-INSTANCE-RECORD
declare
cur_block varchar2(40) := :System.Cursor_Block;
cur_itm varchar2(40);
begin
cur_itm := Get_Block_Property( 'my_block', FIRST_ITEM );
-- focus
if ( cur_itm is not null and :GLOBAL.my_var != 0) then
while( cur_itm is not null ) loop
Set_Item_Instance_Property( cur_itm, CURRENT_RECORD, VISUAL_ATTRIBUTE, 'high');
cur_itm := Get_Item_Property( cur_itm, NEXTITEM);
end loop;
-- defocus
cur_itm := Get_Block_Property( 'T_ALL', FIRST_ITEM );
while( cur_itm is not null ) loop
Set_Item_Instance_Property( cur_itm, to_number(:GLOBAL.my_var), VISUAL_ATTRIBUTE, 'normal');
cur_itm := Get_Item_Property( cur_itm, NEXTITEM);
end loop;
end if;
end;

--
cheers