gtk-text-buffer-delete-selection (buffer &key interactive editable)

buffer -- a gtk-text-buffer object
interactive -- a boolean whether the deletion is caused by user interaction
editable -- a boolean whether the text buffer is editable by default

A boolean whether there was a non-empty selection to delete.

Deletes the range between the "insert" and "selection_bound" marks, that is, the currently selected text. If the interactive argument is true, the editability of the selection will be considered, users cannot delete uneditable text.