What is the code that makes up these Window(gui?)?

I think Blender is made in python.
So what are these windows(GUI?) made of?
(Which GUI library do you use?)
PySide2?PyQt?

Is there a way to see the code that makes up these GUI’s in the Script Editor?
キャプチャ16

キャプチャ18

If you want to see the source of a part of UI:

First enable Developer Extra’s:

  • Edit > Preferences > Interface. Enable: Developer Extras.

Then in the 3D view port click with the right mouse button on a menu item, the Magnet for example (the button Increment won’t work).
Next is to open the Text Editor and Browse (icon with a paper with written text) to the .py file that is now loaded in Blender, available for the Text Editor to open.

It’s indeed made with Python, Blender’s API.

Is it correct to use Edit Source with the right-click?

  • Quick Favorite: Not working.
  • Save changes to “Untitled” before closing: Not working.
  • Magnet Icon: Worked.
  • Timeline: Not working.
    Not working means that the Edit Source was not displayed.

If I want to know how Ctrl+Shift+S and then ± to raise the number of the file, I get the following error when I do Edit Source with the + icon.
bpy.context.scene.tool_settings.snap_elements = {‘INCREMENT’}
Active button is not from a script, cannot edit source
bpy.context.space_data.params.filename = “test_1.blend”
Active button is not from a script, cannot edit source

Save as is: bpy.ops.wm.save_as_mainfile()
You can find such out by clicking: File > Right Click on Save As > Copy Python command
And paste somewhere, for example in Notepad to see what the command is.

You can also click on Online Python Reference, and then you end up here.

Sometimes the Info editor type might give a clue.
Often it’s also a matter of searching online.