imshell: Dear ImGui apps on every platform.

## The whole app

A delegate draws a frame; imshell::Run does the rest. The same file builds for every platform above.

#include "imshell/app.hpp"
#include "imshell/button.hpp"

struct Hello : imshell::Delegate {
    int clicks = 0;
    void frame() override {
        const imshell::Rect r = imshell::ContentRect(); // under the title bar, inside the safe area
        ImGui::SetNextWindowPos(r.pos);
        ImGui::SetNextWindowSize(r.size);
        ImGui::Begin("hello", nullptr, ImGuiWindowFlags_NoDecoration);
        if (imshell::Button("Click me", imshell::ButtonVariant::Primary))
            ++clicks;
        ImGui::Text("Clicked %d times", clicks);
        ImGui::End();
    }
};

int main() {
    static Hello hello;
    return imshell::Run({.title = "Hello", .titleBar = true}, hello);
}

In CMake, next to your own Dear ImGui:

set(IMSHELL_IMGUI_DIR ${CMAKE_CURRENT_SOURCE_DIR}/external/imgui)
add_subdirectory(external/imshell)
add_executable(app main.cpp ${IMGUI_SOURCES})
target_link_libraries(app PRIVATE imshell::imshell) # + imshell::components, optional

Getting started →

## What it has

• * Platform shell: the window, the graphics backend, input, and a loop that idles when nothing changes and skips frames identical to the last.
• * Title bar: draw your own bar in ImGui; imshell keeps the OS buttons, dragging, snap layouts and double-click zoom.
• * Touch: tap to click, long press for menus or the text toolbar, drag to scroll with momentum.
• * Native views: a real NSView, UIView, HWND or GtkWidget (a text field, a map, a web view) in the ImGui layout.
• * Themes and widgets: eighteen palettes; buttons, selects, toggles, splitters, spinners, menus and modal alerts that follow them.
• * Components: optional text fields, cards, badges, callouts, progress, avatars, metrics, chips and toasts.
• * Editor: an optional code editor: selection, undo, find and replace, with highlighting and completion as hooks.
• * Fonts and files: one UI font from a text font, icon fonts and the system's CJK font; file dialogs; fonts and images baked into the binary.
• * Auto-update: Sparkle, WinSparkle or a checked AppImage swap, behind one call.

## Performance

Native code and a loop that sleeps when nothing changes: small binaries, a first frame in milliseconds, and an idle window that costs next to nothing.

Apple M4, 16 GB, macOS 27.0.1, imshell f1a00de, 2026-11-11. hello is the repo's example app: a title bar, buttons and two native views (a text field and a date picker). gallery has every component and the code editor, and never idles: its loading skeleton and progress bar redraw every frame, so its CPU is the cost of animating. Release builds with Dear ImGui, imshell and GLFW linked in, stripped. First frame: from launching hello until it has drawn its first frame and quit, the median of 11 runs. Memory: the physical footprint 3 s after launch. CPU: the time used over the next 10 s, the window focused and left alone. In the browser: the gallery's .wasm and .js as this site serves them (brotli), 279 + 35 KB. Windows, Linux and the phones are not measured yet. site/bench.sh measures it again.