Clearing the gtk_text box

[s k <gtk_som yahoo com>]

Hi,
    Im developing a test application for a driver and
i have a text box that takes text from the user as
input to a databuffer and this databuffer is sent down
to the driver whenever i click a button that issues an
ioctl to the driver

Now i have 2 problems related to this:
1. Firstly i want to limit the text the user can input
i.e after the user types in say some 512 chars the
cursor must automatically stop indicating thats the
max input it can take ...right now i have linewrap on.
2. After writing some text ,and click of the 'Issue'
button i use gtk_backward_delete(gtk_text_length) to
clear off the text that was there and this seems to
work fine as long as the text is not changed between
button clicks..now the moment i change the text say
for eg after one button click if the text was say
'sam' ,then  i click 'Issue' and then before the next
click if i (user ) deletes sam and writes 'ram' and
then clicks the 'Issue' button the previous text ie
sam gets conatenated to give me 'ramsam' which is not
what i want ...
Please let me know how i can clear off the contents of
the text box after each click of the 'Issue 'Button?

Thanks n Regards
Som


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