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0.35.0 - Inspection, egui_mcp, classes and improved IME

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@lucasmerlin lucasmerlin released this 25 Jun 18:44
· 1 commit to main since this release
0.35.0
f72eaf6


egui is an easy-to-use immediate mode GUI for Rust that runs on both web and native.

Try it now: https://www.egui.rs/

egui development is sponsored by Rerun, a startup building an SDK for visualizing streams of multimodal data.

Highlights

  • New egui_mcp crate based on eguis new inspection protocol
  • Set classes on your Uis to modify widget behavior based on surrounding context
  • Improved IME

Egui inspection and egui_mcp

This release includes a new inspection protocol for egui. It allows reading the accesskit tree of a running app, as well
as sending events to control it. It's implemented via a new InspectionPlugin in the egui_inspection crate.
Eframe includes a new inspection feature. When enabled, you can enable inspection by launching the app with
EGUI_INSPECTION=1. This will cause the app to listen on port 5719.

The first inspection protocol consumer is egui_mcp.
It's a mcp server that allows your agent to see and use
egui apps. It can be used to have the agent use the app, reproduce bugs and verify its changes.
Install it via cargo install --git https://github.com/rerun-io/kittest_inspector egui_mcp and then add it to your
agent via claude mcp add egui egui-mcp.

There is also a plan of adding a general inspection gui using the same protocol, that can e.g. be used to step through
kittest tests frame by frame.

Here is claude using the mcp to try some of the egui demos (sped up by a lot, claude is slow):

Screen.Recording.2026-06-25.at.19.58.20.15s.mov

Classes

As part of css like styling, we've added classes to egui. You can already
use them to e.g. modify widget behavior or styling based on surrounding context.
Add classes to the container:

ui.scope_builder(UiBuilder::new().with_class("my_container"), |ui| {
    ...
});

In your widget, check if we're in my_container, to e.g. change sizes or colors:

  let in_container = ui.stack().iter().any(|s| s.classes.has("my_container"));

Today this only works for custom widgets and ui code, but the next step will be a styling system that allows you to modify built
in widget styling based on these classes.

Better IME composition

IME visuals received an overhaul, they are now indicated by an underline and properly show the cursor during composition:

After-macOS-CMN-small.mp4
  • Implement proper visuals for IME composition #8083 by @umajho

⭐ Added

🔧 Changed

  • Improve IME handling, add public method owns_ime_events on Memory #7983 by @umajho
  • Use harfrust for better kerning and ligatures #8031 by @gcailly
  • Rework Window margins and set clip_rect_margin to zero #7725 by @emilk
  • Slide panels when animating them #8175 by @emilk
  • Slow down animation time from 0.1s to 0.2s #8176 by @emilk
  • Smoother CollapsingHeader animation #8177 by @emilk
  • Drag-to-scroll: now only on touch screens #8181 by @emilk
  • Window: move only by dragging title bar #8183 by @emilk
  • Rename Panel methods #8192 by @emilk
  • Panels: double-click resize edge to toggle #8193 by @emilk
  • Rename AlphaFromCoverage to FontColorTransferFunction #8201 by @emilk
  • Smoother collapsed-panel animation #8202 by @emilk
  • Improve Debug-formatting of Id in debug-builds #8190 by @emilk
  • Use strongly typed CharIndex and ByteIndex + bug fixes #8245 by @emilk
  • Allow downscaling image in GetScreenshot inspection request #8248 by @lucasmerlin
  • Announce pressed state of selectable buttons to screen readers #8130 by @antoinecellerier
  • Pre-populate font variation axes in the FontTweak UI #8258 by @emilk
  • Make font hinting target configurable via FontTweak #8262 by @emilk

🔥 Removed

🐛 Fixed

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