examples: Update to glium 0.31

That somehow makes rustdoc-stripper happier?

Gir.toml: Add bool_return_is_error on activate_action_variant

Fixes #762

Regenerate with latest gir (gboolean return codes)

Signed-off-by: Hanif Ariffin <[email protected]>

No longer needed

if the xlib feature is not used, instead of completely ignoring those functions
that returns a X...

This chapter talks about CSS.

More specifically:
- style classes
- names
- pseudo-classes
...

Fixes #558

gtk: manually implement callback getters

Those can't be safely binded from Rust for various reasons.
See https://github.com/gtk-rs/gtk4-r...

It can return VoidSymbol for not found keyvals, so let's use Option there instead

To make it similar to add_region

was a copy paste of the x11_display

Regenerate with latest gir (assert safe gerror)

This refreshes the submodule, i.e. `git submodule update --remote --init gir`.

gtk4: manually implement gtk_print_operation_get_error

Update gir for new builder #[must_use] usage

... or improve their messages a bit.

See https://github.com/gtk-rs/gir/pull/1280

examples: Fix up virtual methods example

Casting a `&glib::Object` to an instance struct only works if all
private types are zero-sized. ...

Regen with gir#1275

Update for glib constructor renames

See https://github.com/gtk-rs/gtk-rs-core/pull/384

docs: opt-in for gi-docgen

regen: update to system-deps 6

To avoid users making use of the From trait
as the FromGlib/IntoGlib traits are unsafe

I don't think it makes sense to allow end-users to change the inner value

we already provide getters/setters

Ideally we would have a simple use case/example there in the future as well
and maybe make gir g...

following what's generated for automatic traits