Is there a more detailed tutorial on creating custom slicer application?

The examples provided on the official website are not detailed enough and hard to learn for me,
so Is there a more detailed tutorial on creating custom slicer application? step by step tutorial and examples, video tutorial will be more better!

There are some on youtube. For example this one:

As far as I know there are no tutorials.
@moraleda the video you linked is about creating an extension, which is different than the question was.

@iwangwangwang You need to follow the steps to create a Slicer custom app skeleton from the template

Then you need to build it just as a Slicer build. You need to add your own modules to the source tree in Modules/ and add them to the main CMakeLists.txt file. Those modules will then be part of your application. You have all the freedom customizing the app, by hiding the toolbar etc.

We have two blogs on the topic: https://www.kitware.com/slicercat-creating-custom-applications-based-on-3d-slicer/

and

https://www.kitware.com/slicercat-and-python-creating-custom-slicer-applications-with-qt-stylesheets/