@ vram overflow
@ keyboard interface

- upgraded blending modes
- blending modes for text
- information masks for text
- test all font encodings
- font clipping

- bitmap parts
- bitmap clipping

- multi-getkey repeats (if possible, which doesn't seem likely)
- it appears that multi-getkey does not always trigger rectangle effects on
  sh7305

- write and test gray engine
- full rtc driver (time)
- callbacks and complete user API

- exhaustive save for setjmp()
- registers that need to be saved when configuring gint

- check possible bug for optimization of __attribute__((interrupt_handler))

- 7305.h
- libc