QT is good but you have other options too... a simpler one would be to use Python with Bash or a simple dialog like Zenity and Bash. If you are familiar with shell scripting that would be the easiest way. Neither Python nor bash would require an DE or SDK to be installed. You could make the Python UI with QT Designer though if you prefer wysiwyg.

The Zenity way would probably be the easiest but maybe not what you are after.