* Use dark-light on Mac and Windows
dark-light has a nasty problem on Linux: https://github.com/frewsxcv/rust-dark-light/issues/17
So we made dark-light opt-in in https://github.com/emilk/egui/pull/1437
This PR makes dark-light a default dependency again,
but only use it on Max and Windows.
This is controlled with the new NativeOptions::follow_system_theme.
If this isn't enabled, then NativeOptions::default_theme is used.
* Add eframe::WebOptions
* Re-implement PaintCallbacks With Support for WGPU
This makes breaking changes to the PaintCallback system, but makes it
flexible enough to support both the WGPU and glow backends with custom
rendering.
Also adds a WGPU equivalent to the glow demo for custom painting.
Based on https://github.com/hasenbanck/egui_wgpu_backend
`egui-wgpu` is now an official backend for `eframe` (opt-in).
Use the `wgpu` feature flag on `eframe` and the `NativeOptions::renderer` settings to pick it.
Co-authored-by: Nils Hasenbanck <nils@hasenbanck.de>
Co-authored-by: Sven Niederberger <niederberger@embotech.com>
Co-authored-by: Sven Niederberger <73159570+s-nie@users.noreply.github.com>
`egui_demo_app/lib`: add "About egui" window, and improve mobile layout
This makes the app responsive, removing the side bars on mobile and turning them into drop-down menus instead.
