Added Wayland support via interactive or non-interactive call

[Photon89]

This PR is based on #817. However, it now tries to use an non-interactive target as defined in flatpak/xdg-desktop-portal#1981. If a target is not yet implemented by a DE, it falls back to an interactive call which shows the DE's interactive mode chooser. As soon as a DE implements the non-interactive targets, Shutter should pick them up and not call the interactive mode chooser any more. Also, the full screen capture is unaffected.

Tested for various DEs:

• For Gnome the interactive mode chooser works quite well. Limitations: The user needs to choose the capture mode again (after having chosen it in Shutter). Filenames are still set to "unknown".
• For KDE the interactive mode chooser seems to offer no selection mode. Also there seems to be no window selection mode, only capturing the active window is possible, which is the mode chooser dialog itself though. So in KDE this PR is basically useless.
• For Cinnamon the interactive mode chooser is not really implemented and always falls back to full screen capture.

Tested non-interactive targets:

• For Cinnamon we are waiting for linuxmint/cinnamon@b780321697ddc1c137557 to be released. But if substituting cinnamon-screenshot with gnome-screenshot, getting screenshot via xdg-desktop-portal-xapp works. The only thing broken is a window chooser (only gets active window instead). Created a feature request for this: https://github.com/orgs/linuxmint/discussions/1548
• For Xfce xdg-desktop-portal-xapp is used so far. I commented here: https://gitlab.xfce.org/xfce/xfce4-session/-/work_items/159

[mvivarelli]

Hi Michael,

I'm Maurizio. I wrote the gnome-screenshot hack for Ubuntu 24.04.

I was looking for a solution to extend Shutter's life on Ubuntu 26.04, where gnome-screenshot no longer works.

I tested your PR just now, and it seems to be a temporary but nevertheless pretty usable solution.

Thanks,

Maurizio

[Photon89]

Hi Maurizio,

great, thanks for testing! As Gnome hasn't implemented non-interactive targets so far, Shutter has to fall back to the interactive mode chooser. That's actually worse than what you have implemented in your PR. And the sad news is that the non-interactive calls will be supposedly forwarded to gnome-screenshot once they have been implemented, so yeah... At least that's what happens in Cinnamon so far.

Let's hope that this will be good enough for potential users. I guess, we've lost many of them due to lacking Wayland support...