"Snapped" form resize like in Delphi 7 Object Inspector

[hwnd]

Run D7, dunno if other versions also have this feature. Make sure you have Object Inspector visible.
Object Inspector is basically grid with specific number of rows.

You can adjust its width to anything you want.

But if you adjust the height (resize it to up or down) then you see like snapping to each row or something like that. Dunno how to say it properly.

The height is adjusted not smoothly but snapping to the height of the rows in Object Inspector grid.


How could that be done?
I dont have Lazarus installed atm, maybe it also has this, i could take a look the source but if not how i could do same thing?

Is the math behind it very difficult?
I would like to make this feature for both width and height fro my editor tile picker window. I like that "snapping".

There are few properties for forms like: "FormCanResize" and "FormConstrainedResize".
Maybe Delphi also uses that. Dunno.

TIA for any tip.