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When using gnome-shell 3.37 this was returning NaN,NaN:
  ```
  let [proposedX, proposedY] = placeholder.get_transformed_position();
  ```
which then led to missing icons:
  ```
  JS LOG: Error adding children to desktop: Not enough place at monitor 0
  ```

So now we force allocation of the grid including placeholders, to ensure
that `get_transformed_position` returns usable coordinates.

Closes: #215

Unstable version of Gnome Shell removed the 'allocation-changed'
signal, so this patch replaces it with notify::allocation.

Fix #206

This MR adds support for templates, AKA "new document". It allows
to copy documents templates into the personal TEMPLATE folder
and create new empty documents from them.

In Gnome Shell master, obtaining the proxy interface for the
SwitcherooControl (which allows to use external GPUs), fails.
This patch tries to fix it by waiting until the Switcheroo
name appears in DBus.

Fix #204

Narrow icons were shown stretched. This patch fixes it.

Fix #205

When the screen size changes (like when a dock is added/removed/
changes possition, or when resolution changes), a lot of errors
are shown. This is because when the grid is reset and the icons
are removed from it, it uses the new size instead the old one
to calculate the number of elements in the grid. This results
in jumping over some locations of the grid, and trying to check
inexistent ones, and thus errors because some elements aren't
removed from the grid.

This patch fixes it by storing the size of the grid during the
initialization, and using that stored value for all operations
untill the grid is reinitialized with a new size.

Use the org.gnome.NautilusPreviewer D-Bus interface, implemented
by sushi.

If a picture changes, the thumbnail isn't refreshed. This
patch ensures that it is refreshed if needed.

In some point between 3.32 and 3.34, the Clutter key symbols changed
from Clutter.XXXX to Clutter.KEY_XXXX. This resulted in the hotkeys
not working.

This patch fixes this.

Fix: #191

Adding support to launch applications with the discrete GPU in dual GPU configurations with render offloading (e.g. NVIDIA Optimus).
This feature is already supported by the GNOME launcher, but is missing for the desktop.
The goal is to have a similar look and feel as the existing launcher feature.

Parts of the implemented code are originated from these locations:
https://gitlab.gnome.org/GNOME/gnome-shell/-/blob/153b7d525d072be5409572b24c74db9c1c84d17a/js/ui/appDisplay.js
https://gitlab.gnome.org/GNOME/gnome-shell/-/blob/0223d38602424e5293305ea57e4523505d9935ee/src/shell-app.c