Best approach to displaying some multi line text data.

[GBanschbach sandata com]

I am a reasonably experienced C programmer, but a total newbie to GTK+, and
glade.  I want to make a 5 line text "window" or panel, and write a
message, then clear it, and write a new message each time one of 3 buttons
is pressed.   I call popen() to get some data and put in onto a window
which already has an hbox with a button bar and a logo.   The data changes
when the user presses each button.   The data might be a 1 line response to
button A,  but 3 or 5 lines to button B.   I DON'T want the text area to
resize the window when the new data arrives each time.