--and-exit does not work on Sway/Wayland

[FabianUntermoser]

Hi there, starting dragon-drop from a wayland terminal breaks the --and-exit feature.
The popup still stays on screen, even if you drag the file somewhere.

Starting it from a terminal using X11, it works.

How can I ensure that dragon-drop is always started under X11?

[trinitronx]

How can I ensure that dragon-drop is always started under X11?

It should be possible for any GTK/GDK-based app to use:

export GDK_BACKEND=x11
# Run your app in this environment

Meanwhile, for any Qt-based app use this instead:

export QT_QPA_PLATFORM=xcb
# Run your app in this environment

In the case of dragon-drop, the GTK example works:

$ export GDK_BACKEND=x11 ; echo -n /tmp/test.png | dragon-drop --stdin
# window spawns

# In another terminal window, we can check `dragon-drop` is running as XWayland client
$ xlsclients
examplex11host  dragon-drop

Due to limitations of drag & drop functionality between Xorg/X11 and Wayland client applications, it's essential that both applications are running under the same display server backend. Either both need to be running as X11 clients, or both need to be Wayland clients.

Using the above two environment variables can help to ensure both apps are running under the same display server protocol backend, so drag & drop can work.

EDIT: This issue is related to #72 because both involve ensuring all apps are using the same display server protocol backend.