/usr/share/SuperCollider/SCClassLibrary/Common/GUI/ is in supercollider-common 1:3.4.5-1wheezy1.
This file is owned by root:root, with mode 0o755.
..
/usr/share/SuperCollider/SCClassLibrary/Common/GUI/Base/
/usr/share/SuperCollider/SCClassLibrary/Common/GUI/Base/EZKnob.sc
/usr/share/SuperCollider/SCClassLibrary/Common/GUI/Base/EZListView.sc
/usr/share/SuperCollider/SCClassLibrary/Common/GUI/Base/EZNumber.sc
/usr/share/SuperCollider/SCClassLibrary/Common/GUI/Base/EZPopUpMenu.sc
/usr/share/SuperCollider/SCClassLibrary/Common/GUI/Base/EZRangerSC.sc
/usr/share/SuperCollider/SCClassLibrary/Common/GUI/Base/EZScroller.sc
/usr/share/SuperCollider/SCClassLibrary/Common/GUI/Base/EZSlider.sc
/usr/share/SuperCollider/SCClassLibrary/Common/GUI/Base/EZText.sc
/usr/share/SuperCollider/SCClassLibrary/Common/GUI/Base/EZgui.sc
/usr/share/SuperCollider/SCClassLibrary/Common/GUI/Base/Gradient.sc
/usr/share/SuperCollider/SCClassLibrary/Common/GUI/ControlModel.sc
/usr/share/SuperCollider/SCClassLibrary/Common/GUI/Document.sc
/usr/share/SuperCollider/SCClassLibrary/Common/GUI/FlowLayout.sc
/usr/share/SuperCollider/SCClassLibrary/Common/GUI/GUI.sc
/usr/share/SuperCollider/SCClassLibrary/Common/GUI/Inspector.sc
/usr/share/SuperCollider/SCClassLibrary/Common/GUI/Model.sc
/usr/share/SuperCollider/SCClassLibrary/Common/GUI/PlusGUI/
/usr/share/SuperCollider/SCClassLibrary/Common/GUI/PlusGUI/Collections/
/usr/share/SuperCollider/SCClassLibrary/Common/GUI/PlusGUI/Collections/StringPlusGUI.sc
/usr/share/SuperCollider/SCClassLibrary/Common/GUI/PlusGUI/Control/
/usr/share/SuperCollider/SCClassLibrary/Common/GUI/PlusGUI/Control/GeneralHIDGUI.sc
/usr/share/SuperCollider/SCClassLibrary/Common/GUI/PlusGUI/Control/ServerPlusGUI.sc
/usr/share/SuperCollider/SCClassLibrary/Common/GUI/PlusGUI/Control/SynthDescLibPlusGUI.sc
/usr/share/SuperCollider/SCClassLibrary/Common/GUI/PlusGUI/Control/SynthDescPlusGUI.sc
/usr/share/SuperCollider/SCClassLibrary/Common/GUI/PlusGUI/Control/UGen-scope.sc
/usr/share/SuperCollider/SCClassLibrary/Common/GUI/PlusGUI/Control/WiiMoteGUI.sc
/usr/share/SuperCollider/SCClassLibrary/Common/GUI/PlusGUI/Control/scopeResponse.sc
/usr/share/SuperCollider/SCClassLibrary/Common/GUI/PlusGUI/Control/server-meter.sc
/usr/share/SuperCollider/SCClassLibrary/Common/GUI/PlusGUI/Control/server-scope.sc
/usr/share/SuperCollider/SCClassLibrary/Common/GUI/PlusGUI/Core/
/usr/share/SuperCollider/SCClassLibrary/Common/GUI/PlusGUI/Core/ClassBrowser.sc
/usr/share/SuperCollider/SCClassLibrary/Common/GUI/PlusGUI/Core/HelperPlus.sc
/usr/share/SuperCollider/SCClassLibrary/Common/GUI/PlusGUI/Core/HistoryGui.sc
/usr/share/SuperCollider/SCClassLibrary/Common/GUI/PlusGUI/Core/KernelPlusGUI.sc
/usr/share/SuperCollider/SCClassLibrary/Common/GUI/PlusGUI/Core/NilPlusGUI.sc
/usr/share/SuperCollider/SCClassLibrary/Common/GUI/PlusGUI/Core/ObjectPlusGUI.sc
/usr/share/SuperCollider/SCClassLibrary/Common/GUI/PlusGUI/Files/
/usr/share/SuperCollider/SCClassLibrary/Common/GUI/PlusGUI/Files/FilePlusGUI.sc
/usr/share/SuperCollider/SCClassLibrary/Common/GUI/PlusGUI/Math/
/usr/share/SuperCollider/SCClassLibrary/Common/GUI/PlusGUI/Math/PlotView.sc
/usr/share/SuperCollider/SCClassLibrary/Common/GUI/PlusGUI/Math/SignalPlusGUI.sc
/usr/share/SuperCollider/SCClassLibrary/Common/GUI/ViewRedirect.sc