Hi!
Previously, I’ve used the gnome-extension pixel-saver ( there is a lot similar, eg: maximus2, no-title-bar … )
But, even if I install the extension with Gnome Software, there is no impact (eg: flatpak of Thunderbird )
IIRC none of them work well on Wayland except one that doesn’t work with Flatpaks. If you really want to ditch the title bar in Evolution, maybe you could try using flatpak override on Evolution with --env=GTK_CSD=0?
Extensions can only remove server-side decorations, that is decorations that have been added by the window manager. They don’t work for decorations added by applications themselves (or the toolkit they use).
Client-side decorations are not only used with custom titlebars (GNOME apps, Firefox, Chromium), but also by wayland applications.
@refi64 Thanks for the suggestion but this doesn’t change anything ( it’s Thunderbird BTW, not Evolution )
@fmuellner Thanks for the explanation, but it’s not Thunderbird that add the decoration, because the extension works correctly with Thunderbird on Fedora 29 / Wayland (the rpm package). This is surely caused by the flatpak.
I don’t see how flatpak would prevent the extension from working.
If it works with Thunderbird on F29, then thunderbird isn’t using its wayland backend. There’s a separate thunderbird-wayland package for a launcher that enables the wayland backend, I bet that would be “broken” as well.
The most likely explanation here is that the thunderbird flatpak uses wayland, while the Fedora package still defaults to X11.
As a side note, I believe the Git version of Pixel Saver or one of the other extension of its type try to work on Wayland by rewriting user-local GTK styles, setting the titlebar style to be shown or hidden and then refreshing the current window or similar (?). It’s a bit of a mess, but if that’s indeed the case, Flatpak wouldn’t pick up on it anyway.