Dear Marek,
clearing EA bit will turn off all the interrupts effectively. and all the interrupt sources including timer over flows will be ignored completely. Anyways during this period when interrupts are off the TF will be set but there won't be any timer interrupt generated [ Even after enabling the interrupts the timer which over flowed when interrupts were disabled won't cause any interrupt immediately. obviously every overflow which occurs while interrupts are active will cause an interrupt.

Regards,
Prahlad Purohit