Other in KDE Base
QListView does not support having a margin for grids.
Originally it has been tried to bypass this by overwriting QListView::visualRect(), but this has some side effects (see #155378 and #155575). The clean approach is to return a proper size hint in the file item delegate.
Currently a custom item delegate has been made for Dolphin, but we'll discuss whether it makes sense providing this feature already in KFileItemDelegate...