Scrollbar on box and windows

Hi,
I created a little software with go for editing csv with your andlabs ui (love it for the portability to all operating system and for its very simple use).
you can see it on: [https://github.com/hfmrow/csveditor](https://github.com/hfmrow/csveditor).

I would be happy to find a way to have a vertical scroll bar for windows and boxes, I mean a fixed size box and/or window with multiple controls (16-18) actually extend the size of the window or box, but the size becomes out of the maximum height range of the on-screen display and the bottom controls are invisible (I can use [alt] + lmb but ...).
Is there a way to have a maximum height of a box and/or window and get a vertical scroll bar when there are too many controls?

For example, you can try to load or create a csv file with more than 18 fields and edit a line, you can see the edit window or an option tab that does not display the last controls or buttons .

I hope I'm clear enough (English is not easy for me ...).
I'm using ubuntu for development.
Thank you for your work.