sorry, typos:
and 3rd,
how to optionally drive the OLEDs on i2c-1 or/and on i2c-0 ?

and 3rd,
how to optionally the OLEDson i2c-1 or/and on i2c-0 ?

another question:
you wrote
" Added millis() function"

But millis() is already provided by Gordon Henderson's WiringPi lib which I always use - I'm afraid that will cause interferences and problems. How can one fix that problem?

hello,
you specified the following types:
0 Adafruit SPI 128x32
1 Adafruit SPI 128x64
2 Adafruit I2C 128x32
3 Adafruit I2C 128x64
4 Seeed I2C 128x64
5 Seeed I2C 96x96
6 SH1106 I2C 128x64

the chip of the 6th is obvious, but which chip types are especially 1,3, and 4?
what about the i2c dev addresses of these OLEDs, and how to change them in the code if needed?

hello,
can you please provide compile/build parameter settings and examples hw to use this lib with Geany, providing system-wide paths to #include the libs from each proprietary source code program located in any different directory?