On some z-wave dimmers like qubino - there is a possibility to connect up to 3 buttons (for example qubino).
I am currently only thinking on implementing z-wave so question is. Can thos two button inputs be used as an input for openhab or the can onlyb be tied to other z-wave devices?
For example can i tie button (input) 2 to fire up a home theater script via openhab?
Yes - you can (normally) set these switches up to either directly link to physical devices, or you can link them to openHAB and use it to trigger a rule.
This is normally done using associations - so you configure the association to send a command to a device, or to openHAB. Have a read of the manual of the device to check it supports associations - most devices do, but there are some that don’t!
Well looking at the manual doesn’t make any sense to newbie
Association
Association enables Flush dimmer module to transfer commands inside
Z-Wave network directly (without main controller) to other Z-Wave modules.
Associated Groups:
Group 1: multilevel (triggered at changes of state/value of the Flush dimmer)
Group 2: basic on/off (triggered at change of the input I2 state and reflecting its state)
Group 3: basic on/off (triggered at change of the input I3 state and reflecting its state)
Group 4: default reporting group (reserved for the main controller)
There’s endpoints 2 and 3 on the device for inputs I2 and I3. Setup a switch type item and link to those.
If you want to directly link to other devices, groups 2 and 3 are for Inputs I2 and I3, respectively. 1 is for I1 (the dimmer) and 4 is the default association for the controller.