window.setWindowTitle Sets the caption of a user window
Usage
window.setWindowTitle [-q] <window_id> <plain_text_caption>
Description
Sets the caption of the user window specified by <window_id> to <plain_text_caption>. If <window_id> is an empty string then the current window is assumed. If the window does not exist then a warning is printed unless the -q switch is used.
Switches

-q | --quiet
Be quiet

Index, Commands