[LVGL] Add user_data to event callbacks

[itarozzi]

Is your feature request related to a problem? Please describe.

At the moment does not exists a way to add user_data to a callback button. I see I can link a button event to an UserAction, but no way to pass user_data to them.

I would like to use same callback for several widgets, but I need to get caller ID or caller data (without using global variables)

Describe the solution you'd like

I would like an edit box in the event panel to assign number or variable name or obj reference. This parameter will be passed to lv_obj_add_event_cb() generated by eez-studio.

Describe alternatives you've considered

I'll try to use variables with Flow assignement, but I don't know if the flow is executed before the event call, so I can check the variable value inside the User Action implementation in my C code

[mvladic]

Implemented.

It is now possible to specify integer user data: