How do you develop an app on Ubuntu with a simple GUI? [closed]

How do you develop an app on Ubuntu with a simple GUI? I have looked everywhere and I can't find a way.

Earlier this year Canonical started to move towards making Flutter one of the “first class” development tools for Ubuntu. If you are experienced with a bit of the web development toolkit (HTML/CSS/JavaScript), then you can quickly adapt to use Flutter to create applications that will run on Ubuntu. There are a number of IDEs that support the language, such as Sublime Text and Microsoft Code, as well as a wealth of online tutorials. Flutter is cross-platform, so can be used to make applications for the major operating systems. As a result, there are a lot of resources online to learn from … though few are Linux-specific.

Check out the example in the link above, or take a look at the main Flutter page, which has far more examples, links to training resources, plus some pretty comprehensive documentation 👍🏻