CellRenderer: Clarify doc of .start_editing()

Drop the line copied from .activate(), replace it with a description of
what this method actually does, and explain what a NULL result means.

https://gitlab.gnome.org/GNOME/gtk/issues/154

diff --git a/gtk/gtkcellrenderer.c b/gtk/gtkcellrenderer.c
index 46f0189a1b0a43f9fd8328ca75f2aa942724d7ee..8abb0bf4d36cdf68a84707395dcebf04de299b32 100644 (file)
--- a/gtk/gtkcellrenderer.c
+++ b/gtk/gtkcellrenderer.c
@@ -798,9 +798,11 @@ gtk_cell_renderer_activate (GtkCellRenderer      *cell,
  * @cell_area: cell area as passed to gtk_cell_renderer_render()
  * @flags: render flags
  *
- * Passes an activate event to the cell renderer for possible processing.
+ * Starts editing the contents of this @cell, through a new #GtkCellEditable
+ * widget created by the #GtkCellRendererClass.start_editing virtual function.
  *
- * Returns: (nullable) (transfer none): A new #GtkCellEditable, or %NULL
+ * Returns: (nullable) (transfer none): A new #GtkCellEditable for editing this
+ *   @cell, or %NULL if editing is not possible
  **/
 GtkCellEditable *
 gtk_cell_renderer_start_editing (GtkCellRenderer      *cell,