workflow customization

[rao.9485]

Hi,

I am having issues with custom workflow i have attached.
My issue 1
-> If i withdrawn a issue it should be read only none of them should change that issue .(I am trying to keep default value as withdrawn but it always going back assigned or new)
2.
- > If i close the issue i don't want to change the status as well. if it's close means it should be close. after that issue should be read only.

$g_status_enum_string = '10:new,20:assigned,30:opened,40:code_completed,50:resolved,60:postponed,70:rejected,80:verified_IT,90:Verified_ST,100:withdrawn,110:closed';
i have enclosed attachment
Please let me know.