TREATMENT CONCURRENT WITH RADIOTHERAPY: Beginning 3-4 weeks after surgery, patients undergo conventional focal (intensity-modulated radiation therapy [IMRT] or 3-D conformal) radiotherapy 5 days a week for approximately 6 weeks. Patients also receive gamma-secretase/Notch signalling pathway inhibitor RO4929097 PO QD for approximately 10 weeks beginning the day of radiotherapy and temozolomide PO QD for approximately 6 weeks beginning the day before radiotherapy.