JavaScript Es geht um die Größeneinstellungen eines Buttons

    init: function() {

        this.handleRelativePath(this.toolbar.apps);
        const XULNS = 'http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul';

        var ExternalAppBtn = document.createElementNS(XULNS, 'toolbarbutton');

        ExternalAppBtn.id = "AppMenuButton";
        ExternalAppBtn.setAttribute("label", "AppButton");
        ExternalAppBtn.setAttribute("onclick", "event.preventDefault();event.stopPropagation();");
        ExternalAppBtn.setAttribute("tooltiptext", "Firefox Menü");
        ExternalAppBtn.setAttribute("type", "menu");
        ExternalAppBtn.setAttribute("removable", "true");

        // Definiere den Profilpfad
        let ProfilePath = PathUtils.toFileURI(PathUtils.join(PathUtils.profileDir, 'chrome', 'image'));

        // Symbole
        let DefaultIcon = "Button_groß.png";
        let AlternateIcon = "Button_klein-plus.png";

        // Wenn Appmenu.isButton true ist, benutze das große Symbol, sonst das kleine
        if (Appmenu.isButton) {
            ExternalAppBtn.style.listStyleImage = `url('${ProfilePath}/${DefaultIcon}')`;  // Großes Symbol
            ExternalAppBtn.style.width = "94px";  // Feste Breite für großes Symbol
            ExternalAppBtn.style.height = "24px";  // Feste Höhe für großes Symbol
        } else {
            ExternalAppBtn.style.listStyleImage = `url('${ProfilePath}/${AlternateIcon}')`;  // Kleines Symbol
            ExternalAppBtn.style.width = "16px";  // Feste Breite für kleines Symbol
            ExternalAppBtn.style.height = "21px";  // Feste Höhe für kleines Symbol
        }
          
        // Button in die richtige Toolbar einfügen          
        if (Appmenu.isUrlbar === 1) {
            var navBar = document.getElementById("nav-bar-customization-target");
            navBar.insertBefore(ExternalAppBtn, navBar.firstChild);
        } else if (Appmenu.isUrlbar === 2) {
            var menubar = document.getElementById("toolbar-menubar");
            menubar.insertBefore(ExternalAppBtn, menubar.firstChild);
        } else {
            var TabsToolbar = document.getElementById("TabsToolbar");
            TabsToolbar.insertBefore(ExternalAppBtn, TabsToolbar.firstChild);
            
        }
        

    var ExternalAppPopup = document.createElementNS(XULNS, 'menupopup');
    //ExternalAppPopup.setAttribute('onpopupshowing', 'event.stopPropagation(); Appmenu.onpopupshowing();');
    ExternalAppPopup.setAttribute('id', 'AMpopup');
    this._externalAppPopup = ExternalAppPopup;
    ExternalAppBtn.appendChild(ExternalAppPopup);
    Appmenu.onpopupshowing();
    
      // Menü mit Tastaturkürzel öffnen
    let key = document.createXULElement('key');
    key.id = 'key_AppMenuPopup';
 //   key.setAttribute('key', 'X');
    key.setAttribute('key', Appmenu.hotkey);
        if (Appmenu.hotkeyModifier)
 //   key.setAttribute('modifiers', 'alt');
    key.setAttribute('modifiers', Appmenu.hotkeyModifier);
    key.setAttribute('oncommand', 'document.getElementById("AMpopup").openPopup();');
    document.getElementById('mainKeyset').appendChild(key);
    },