desktop: Make clipboard support optional

[ColinKinloch]

On Wayland ruffle uses https://github.com/YaLTeR/wl-clipboard-rs which only supports wlr-data-control-unstable-v1 which is not intended to be supported by all compositors.

There are options with better support https://wayland.app/protocols/primary-selection-unstable-v1 but until it's implemented in wl-clipboard-rs ruffle will crash for want of clipboard access.

For most platforms this MR wont effect anything. On platforms without clipboard support it'll quietly fail to set and get the clipboard.

Fixes #15213

Mutter doesn't intend to support it: https://gitlab.gnome.org/GNOME/mutter/-/issues/524

[torokati44]

Thank you!
We really should get to the bottom of this Wayland protocol mess someday...

[evilpie]

Thank you! We really should get to the bottom of this Wayland protocol mess someday...

Second! I really hope wl-clipboard-rs or arboard can figure this out for us 😃

[torokati44]

Well, of course... 😅
Or smithay-clipboard, that we're currently directly using.

[torokati44]

Oh, and welcome, new contributor! 👋 😄

[torokati44]

Speaking of - could you please raise this to https://github.com/Smithay/smithay-clipboard/issues as well, @ColinKinloch?
Seems like you have a better understanding of all these protocols and their implementation statuses than us...

[ColinKinloch]

could you please raise this to smithay-clipboard

Smithays fine, I'm currently looking into whether I can use it in place of arboard.

On that, do you have any example swf files that access the clipboard?

[torokati44]

I meant the wlr-data-control-unstable-v1 vs. primary-selection-unstable-v1 thing.
Sounded to me like these are alternatives of each other...?

[torokati44]

On that, do you have any example swf files that access the clipboard?

Yeah, see: #6476 (comment)
Proper link in this comment, steps to reach clipboard usage in the original description.

[ColinKinloch]

In wayland the clipboard is defined in the core protocol by wl_data_device::selection and wl_data_device::set_selection.

wlr-data-control-unstable-v1 seems to be for creating a "clipboard manager" which seems to be a client that is allowed to manage the clipboard.

"primary selection" refers to the ability to use middle click to paste the last highlighted text.

egui_winit::clipboard::Clipboard seems like an easy option as it's already in the dependency tree and wraps both arboard and smithay-clipboard. However in testing it in a flatpak sandbox it still seems to require x11 (XWayland) to access the system clipboard.