It is compatible with the GPIO board. Each button that is connected has a pull-up to 3.3V. The buttons connect them to ground, so they are all active low.
Pin 26 in the GPIO connector is not connected to anything but just to confuse people it is GPIO7. GPIO26 is on GPIO connector pin 37 and used for OSD. The power button is GPIO pin 36, which corresponds to GPIO16.
I am sure the use of GPIO physical pins as GPIO ports with different numbering has caused no end of confusion and many re-worked PCBs.