how to create custom form like the dropdown window when click "create" in sugar 7

Hi All, 

I have been working on sugar 6 but i am quite new to sugar 7.

i have a requirement:

when on a client record view, click a custom button (added) --> open a new form, on which user can do more operation related to the current client (the current client id should be able to pass to this new form).   

I have tried to create custom layout, but i have difficulty to pass the current client id to the custom view?

I have been reading the documentations and do google search. but i could not find any useful example. 

It should be a quite simple and common task. could anyone give some help or guide? Do you guys use app.drawer.open to achieve this kind of customisation?

thanks a lot.