Appending into a text box?

I have a custom page with a large multiline text area.

I'd like to fill this text area in with the contents of a file (say 2-3k in size) if the file exists. The user can edit/hack this content to their desire.

If the file does not exist then I want the user to have the ability to cut-n-paste content into this text area (which will later be saved to a file).

My issue. How do I append into a text area from my NSIS script one line at a time (e.g. from the output of FileRead)?
Is it even possible?

I know I can append into a list box, but I can not use a list box in this case because the user needs to be able to edit and add content.

The FileRead function works on a line by line basis. Hence, I believe I need to append into the text area as soon as a line has been read. Note, I can not append up a big string with the file content and then do a single WM_SETTEXT due to 1024 string length issues (my content may be more than 1024 characters).

Is there some type of appending to text area 'SendMessage' I can use?

Multiple "SendMessage .. ${WM_SETTEXT} .." will not work since each SendMessage will overwrite rather than append to the text area.

Gee, I hope "Text" controls can do what I want to do.

Any assistence would be grateful.

Dennis.

Re: Appending into a text box?

Oops, sorry for wasting anyone's time.

I think I figured it out.

FileRead $0 $1
SendMessage $R1 ${EM_REPLACESEL} 0 "STR:$1"

appears to work.

Sorry, I'm just coming up to speed with the loveliness that is Windows GUI programming.

Dennis.

You'd need the special 8k nsis build.
Append each line of the text to a variable as described here,

and finally add it to the text field.