Не пойму как там сверстано - но вот так работает:
Пока попробовал только в google chrome
PHP код:
top.TYPO3.Backend.NavigationContainer.hide();
window.top.document.getElementById("typo3-navigationContainer-xsplit").style.visibility = "hidden";
window.top.document.getElementById("ext-comp-1004").style.left = "0px";
window.top.document.getElementById("ext-comp-1004").style.width = window.top.document.getElementById("ext-comp-1003").style.width;
window.top.document.getElementById("typo3-contentContainerWrapper").style.width = window.top.document.getElementById("ext-comp-1003").style.width;
window.top.document.getElementById("typo3-contentContainer").style.width = window.top.document.getElementById("ext-comp-1003").style.width;
window.top.document.getElementById("ext-gen55").style.width = window.top.document.getElementById("ext-comp-1003").style.width;
window.top.document.getElementById("ext-gen38").style.width = window.top.document.getElementById("ext-comp-1003").style.width;
window.top.document.getElementById("ext-gen29").style.width = window.top.document.getElementById("ext-comp-1003").style.width;
window.top.document.getElementById("ext-gen58").style.width = window.top.document.getElementById("ext-comp-1003").style.width;