[Libreoffice] about insert in tool bar in the writer

hi ,
I added a top-down left-right button  in toolbar (called .uno VerticalTextL2R), and add it to the 
model Presentation and Drawing successfully but failed in Writer.
I know to add a  button, first modify some xml file, and I did it these model and worked, and then 
add some function in .sdi file, that handle the button events, but I can't find where the Writer's 
function to be added(I have finded the sdi file to sd and sc).
please give me some advice or tell me who can help me?


thank you.