Starts editing the contents of this this, through a new `GtkCellEditable` widget created by the `GtkCellRenderer`Class.
start_editing virtual function.
| this |
a `GtkCellRenderer` |
| event |
a `GdkEvent` |
| widget |
widget that received the event |
| path |
widget-dependent string representation of the event location; e.g. for `GtkTreeView`, a string representation of `GtkTreePath` |
| background_area |
background area as passed to render |
| cell_area |
cell area as passed to render |
| flags |
render flags |
|
A new `GtkCellEditable` for editing this this, or null if editing is not possible |