ModularUIWindow

Since 2.2.34

ModularUIWindow hosts a ModularUI in a second operating-system window. The UI still uses the ordinary LDLib2 rendering and input path, but can be moved to another monitor.

The editor's Scene view after being detached into a native window. Its LDLib2 content and controls continue to render normally.

var window = new ModularUIWindow(new ModularUI(UI.of(root)), "My Tool");
window.setDragArea(titleBar);              // optional
window.setStyleSource(parentModularUI);    // optional: follow its theme
if (!window.open(Integer.MIN_VALUE, Integer.MIN_VALUE, 640, 400, false)) {
    // Open the same UI in the Minecraft window instead.
}

API	Description
open(x, y, width, height, decorated)	Creates and shows the native window. Use Integer.MIN_VALUE for platform placement.
close() / isOpen()	Closes or checks the hosted window.
setDragArea(UIElement)	Makes an element act as the title bar drag region.
setStyleSource(ModularUI)	Mirrors runtime stylesheets from an originating UI.
setResizable(boolean)	Enables edge resizing.
setOnCloseRequested(Runnable)	Handles the user close request.
setTitle(String)	Renames the window, including the OS title if it is open.
isMaximized() / toggleMaximized()	Reads or toggles the maximized state.
isDragBlocker(UIElement)	Protected. Override so presses on your own title bar controls are not taken as a window move. Buttons are blockers by default.
surface()	The off-screen target the UI is drawn into, or null before opening. Useful for tests and captures.
openWindows()	Static. Every open ModularUIWindow, in opening order.
windowOf(ModularUI)	Static. The window hosting a UI (or the UI it is embedded in), or null if it is drawn in the game window.
MIN_WIDTH / MIN_HEIGHT	The resize floor, 200 × 150 window pixels. Clamp computed sizes to it.

Remember Where a Window Was

Since 2.2.38

API	Description
restoredBounds()	Where the window was the last time it was open and not maximized, as a WindowBounds, or null. Sampled every frame, so it survives the window being closed or the game being killed.
WindowBounds(x, y, width, height)	A window rectangle in virtual-screen pixels, not GUI units. atLeastMinimum() clamps it to MIN_WIDTH × MIN_HEIGHT.
setAlwaysOnTop(boolean) / isAlwaysOnTop()	Keeps the window above all others, including the game window. Does nothing where the platform refuses.

Keep the result of restoredBounds() when your tool closes, and pass it back to open(...) next time:

// on close
savedBounds = window.restoredBounds();

// next time
var b = savedBounds == null ? null : savedBounds.atLeastMinimum();
boolean opened = b == null
        ? window.open(Integer.MIN_VALUE, Integer.MIN_VALUE, 640, 400, false)
        : window.open(b.x(), b.y(), b.width(), b.height(), false);

OsWindow.supportsAlwaysOnTop() is false on Wayland. Hide an always-on-top control there instead of offering one that does nothing.

Built-in Uses

Window	What it hosts	Since
FloatingViewWindow	An editor view torn out with Float in New Window. See Floating Views.	2.2.34
UIDebuggerWindow	The UI debugger. See Debug your UI.	2.2.38
EditorOsWindow	A whole editor. See Open the Editor in Its Own Window.	2.2.42

Client-only and optional

This API is client-only. open(...) returns false if a second window cannot be created; callers must provide an in-game fallback. Keep decorated as false unless platform-managed move/resize behavior is explicitly required.

A hosted window uses the game window's GUI scale. It cannot have its own.