I have created a custom sub grid for adding quote product lines in Quote entity.  Because I would like to add quote product by using Quick create form .  In Core subgrid,  I couldn't able to integrate the Quick create form.  Now,  my problem is, in the custom grid,  I couldn't see the Bundle associated products.  The "Collapse" icon option is not visible in my custom grid.  Is it possible to show the collapse icon in the custom grid.  Kindly find below the screen shot.  The first grid is without "Expand/Collapse" icon which is custom grid.  The second grid Core grid with "Expand/Collapse" icon.

Classic View :

Unified Interface View :