/usr/share/SuperCollider/SCClassLibrary/crucial/Gui/ is in supercollider-common 1:3.4.5-1wheezy1.
This file is owned by root:root, with mode 0o755.
..
/usr/share/SuperCollider/SCClassLibrary/crucial/Gui/ActionButton.sc
/usr/share/SuperCollider/SCClassLibrary/crucial/Gui/CXLabel.sc
/usr/share/SuperCollider/SCClassLibrary/crucial/Gui/CXMenu.sc
/usr/share/SuperCollider/SCClassLibrary/crucial/Gui/GridLayout.sc
/usr/share/SuperCollider/SCClassLibrary/crucial/Gui/MLIDbrowser.sc
/usr/share/SuperCollider/SCClassLibrary/crucial/Gui/ObjectGui.sc
/usr/share/SuperCollider/SCClassLibrary/crucial/Gui/PageLayout.sc
/usr/share/SuperCollider/SCClassLibrary/crucial/Gui/SelectButtonSet.sc
/usr/share/SuperCollider/SCClassLibrary/crucial/Gui/StringGui.sc
/usr/share/SuperCollider/SCClassLibrary/crucial/Gui/SynthConsole.sc
/usr/share/SuperCollider/SCClassLibrary/crucial/Gui/Updater.sc
/usr/share/SuperCollider/SCClassLibrary/crucial/Gui/gui.sc