add a new plugin hook `afterOnCellMouseOver`
native scrollbars: don't call `onDraw` callback (HOT `afterRender` plugin hook) in Walkontable overlays
native scrollbars: adjust pixel overhead of fill handle/box shadow
native scrollbars: remove redundant variable
native scrollbars: reposition scrollbar overlays after CSS change in the document
native scrollbars: cache row height after render
native scrollbars: with native scrollbars a cell size can safely exceed the width of the viewport
native scrollbars: if I have 2 fixed columns with one-line content and the 3rd column has a multiline content, this is the way to make sure that the overlay has the same row height
native scrollbars: at this point the cached row heights may be invalid, but it is better not to reset the cache, which could cause scrollbar jumping when there are multiline cells outside of the rendered part of the table