Server Raspberry Pi3 GPIO Access

hi,

i saw the "AV & Custom Systems (File)" driver. so i thought it would be possible to directly use the GPIO pins of a raspberry while running as iridium server?

when activating some GPIO pins in /sys/class/gpio/" via setting it up with export and then direction, etc. i can see that entry on the iridium server webgui GPIO tab. it also shows the current direction move and the value. but i was not able to set a value from within the webgui. 

can you provide us with a short example how to directly use a GPIO pin with the "AV & Custom Systems (File)" driver on the RPi3?

or do we have to use command line calls instead? 

thx.

martin