Added basic GTK window handling

pkgs/clan-vm-manager/README.md

@@ -0,0 +1,61 @@
+## Developing GTK3 Applications
+
+Here we will document on how to develop GTK3 application UI in python. First we want to setup
+an example code base to look into. In this case gnome-music.
+
+## Setup gnome-music as code reference
+
+gnome-music does not use glade
+
+Clone gnome-music and check out the tag v40.0
+[gnome-music](https://github.com/GNOME/gnome-music/tree/40.0)
+
+```bash
+git clone git@github.com:GNOME/gnome-music.git && cd gnome-music && git checkout 40.0
+```
+
+Checkout nixpkgs version `468cb5980b56d348979488a74a9b5de638400160` for the correct gnome-music devshell then execute:
+
+```bash
+
+nix develop /home/username/Projects/nixpkgs#gnome.gnome-music
+```
+
+Look into the file `gnome-music.in` which bootstraps the application.
+
+## Setup gnu-cash as reference
+
+Gnucash uses glade with complex UI
+Setup gnucash
+
+```bash
+git clone git@github.com:Gnucash/gnucash.git
+git checkout ed4921271c863c7f6e0c800e206b25ac6e9ba4da
+
+cd nixpkgs
+git checkout 015739d7bffa7da4e923978040a2f7cba6af3270
+nix develop /home/username/Projects/nixpkgs#gnucash
+mkdir build && cd build
+cmake ..
+cd ..
+make
+```
+
+### Glade
+
+Make sure to check the 'composit' box in glade in the GtkApplicationWindow to be able to
+import the glade file through GTK template
+
+## Links
+
+- Another python glade project [syncthing-gtk](https://github.com/kozec/syncthing-gtk)
+
+- Other python glade project [linuxcnc](https://github.com/podarok/linuxcnc/tree/master)
+
+- Install [Glade UI Toolbuilder](https://gitlab.gnome.org/GNOME/glade)
+
+- To understand GTK3 Components look into the [Python GTK3 Tutorial](https://python-gtk-3-tutorial.readthedocs.io/en/latest/search.html?q=ApplicationWindow&check_keywords=yes&area=default)
+
+- Also look into [PyGObject](https://pygobject.readthedocs.io/en/latest/guide/gtk_template.html) to know more about threading and async etc.
+- [GI Python API](https://lazka.github.io/pgi-docs/#Gtk-4.0/classes/ApplicationWindow.html#Gtk.ApplicationWindow)
+- https://developer.gnome.org/documentation/tutorials/application.html