For extension developers.
Most extensions to Inkscape use an .inx file that describes a static user interface, then a Python script is run one time when the user clicks "Apply".
To create a dynamic UI (that changes as the user clicks buttons, selects from dropdown menus, etc) you can build it in GTK using a Python script that runs immediately. Requires Inkscape v1.1 or newer.
These short examples demonstrate a handful of functions in GTK+ 3.
Now includes an example extension that uses a .glade XML file to create the UI with Gtk.Builder(). Also many small changes that result in much higher pylint code scores.
this sill cannot send data back to XML until extetion is running right ?