Adds sibling to renderer's focusable area, focus will be drawn around renderer and all of its siblings if renderer can focus for a given row. Events handled by focus siblings can also activate the given focusable renderer.
the GtkCellRenderer expected to have focus
the GtkCellRenderer to add to renderer's focus area Since 3.0
See Implementation
Adds sibling to renderer's focusable area, focus will be drawn around renderer and all of its siblings if renderer can focus for a given row. Events handled by focus siblings can also activate the given focusable renderer.