SelectionTool: support drag-deselecting when holding ctrl
SelectionTool: support drag-deselecting when holding ctrl

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