I'm working for small company, which operates in the automation industry.
The boss hired me because he wants to sell/give some desktop applications to his
current costumers.
He imposes me to use the Netbeans Platform (a generic desktop application framework).
A software engineer friend of his advised him to choose this framework. 
At the moment I created 3 desktop applications with Netbeans Platform.
I like Netbeans Platfom. I really take advantage of modularity, Window System and Lookup.
Unfortunately I'm frustrated to known that I can do the same works with Python and PyQt in a fraction of time.
I've already illustrated to my boss the main advantages of Python, but he doesn't like the
idea to use a language that he never heared of it.
I'm the only programmer who codes desktop applications. And except the framework imposition, I'm free to use whatever I want.
I'm looking for good motivations to convince him to leave Netbeans Platform for Python/PyQt.
P.S: My english is bad, sorry.
Some people will tell you to try to convince your boss verbally. Others will tell you to document the time savings you think you can make. My opinion is that you just go ahead and do it. Do it in your own time if you strongly believe its in your best interests.
I'm yet to meet a software manager who turned down a working piece of software when it comes in on time and under budget. This is by far the best method of persuasion I've used in my career. Its also a great way to show you have initiative. Just be prepared to work for free if it doesnt work out.
How to convince boss to substitute Java/Netbeans Platform for Python/PyQt?