Originale Übersetzungfenster mit Maus frei verschieben?

// ==UserScript==
// @name           Übersetzungs-Popup verschieben.uc.js
// @description    Macht das Firefox-Auswahlübersetzungs-Popup verschiebbar
// @version        2.0
// @autor          ChatGPT
// ==/UserScript==

(function () {
    "use strict";

    const PANEL_ID = "select-translations-panel";
    const HEADER_ID = "select-translations-panel-header-row";

    let panel = null;
    let dragging = false;

    let startMouseX = 0;
    let startMouseY = 0;
    let startPanelX = 0;
    let startPanelY = 0;

    function getPanelFromNode(node) {
        while (node) {
            if (node.id === PANEL_ID) {
                return node;
            }

            node = node.parentNode;
        }

        return null;
    }

    function isHeader(node) {
        while (node) {
            if (node.id === HEADER_ID) {
                return true;
            }

            if (node.id === PANEL_ID) {
                return false;
            }

            node = node.parentNode;
        }

        return false;
    }

    function onMouseDown(event) {
        if (event.button !== 0) {
            return;
        }

        const target = event.originalTarget || event.target;

        if (!isHeader(target)) {
            return;
        }

        const p = getPanelFromNode(target);

        if (!p) {
            return;
        }

        // Nicht anfangen zu ziehen, wenn der Mauszeiger
        // über dem Einstellungs-Zahnrad liegt.
        let node = target;

        while (node && node !== p) {
            if (node.id === "select-translations-panel-settings-button") {
                return;
            }

            node = node.parentNode;
        }

        panel = p;
        dragging = true;

        startMouseX = event.screenX;
        startMouseY = event.screenY;

        const rect = panel.getBoundingClientRect();

        /*
         * Das Panel sitzt innerhalb des Browserfensters.
         * screenX/screenY des Browserfensters plus die
         * Panelposition ergeben die Bildschirmkoordinaten.
         */
        startPanelX = window.mozInnerScreenX + rect.left;
        startPanelY = window.mozInnerScreenY + rect.top;

        event.preventDefault();
        event.stopPropagation();

        window.addEventListener("mousemove", onMouseMove, true);
        window.addEventListener("mouseup", onMouseUp, true);
    }

    function onMouseMove(event) {
        if (!dragging || !panel) {
            return;
        }

        const dx = event.screenX - startMouseX;
        const dy = event.screenY - startMouseY;

        const x = Math.round(startPanelX + dx);
        const y = Math.round(startPanelY + dy);

        try {
            panel.moveTo(x, y);
        } catch (e) {
            console.error(
                "[Translation Popup] moveTo() fehlgeschlagen:",
                e
            );
        }

        event.preventDefault();
        event.stopPropagation();
    }

    function onMouseUp(event) {
        if (!dragging) {
            return;
        }

        dragging = false;

        window.removeEventListener("mousemove", onMouseMove, true);
        window.removeEventListener("mouseup", onMouseUp, true);

        panel = null;
    }

    function setupPanel(p) {
        if (!p || p.dataset.movableTranslationPopup) {
            return;
        }

        p.dataset.movableTranslationPopup = "true";

        const header = p.querySelector("#" + HEADER_ID);

        if (header) {
            header.style.setProperty(
                "cursor",
                "move",
                "important"
            );
        }
    }

    /*
     * popupshowing direkt am Browserfenster überwachen.
     */
    window.addEventListener(
        "popupshowing",
        function (event) {
            const p = event.originalTarget;

            if (p && p.id === PANEL_ID) {
                setupPanel(p);
            }
        },
        true
    );

    /*
     * Zusätzlich globale Mausüberwachung.
     * Dadurch funktioniert es auch dann, wenn das Popup
     * bereits existierte, bevor unser Handler angesprungen ist.
     */
    window.addEventListener(
        "mousedown",
        onMouseDown,
        true
    );

    /*
     * Falls das Panel beim Laden schon vorhanden ist.
     */
    const existing = document.getElementById(PANEL_ID);

    if (existing) {
        setupPanel(existing);
    }

})();