StyleSheet : Fix empty TabContainer backgrounds
StyleSheet : Fix empty TabContainer backgrounds

GafferHQ/gaffer,lucienfostier/gaffer,ImageEngine/gaffer,hradec/gaffer,lucienfostier/gaffer,boberfly/gaffer,GafferHQ/gaffer,johnhaddon/gaffer,boberfly/gaffer,johnhaddon/gaffer,andrewkaufman/gaffer,andrewkaufman/gaffer,hradec/gaffer,johnhaddon/gaffer,boberfly/gaffer,appleseedhq/gaffer,johnhaddon/gaffer,andrewkaufman/gaffer,boberfly/gaffer,lucienfostier/gaffer,andrewkaufman/gaffer,ImageEngine/gaffer,hradec/gaffer,hradec/gaffer,GafferHQ/gaffer,hradec/gaffer,appleseedhq/gaffer,johnhaddon/gaffer,GafferHQ/gaffer,lucienfostier/gaffer,appleseedhq/gaffer,appleseedhq/gaffer,GafferHQ/gaffer,ImageEngine/gaffer,ImageEngine/gaffer,andrewkaufman/gaffer