insert_before

Description:

public void insert_before (Widget parent, Widget? next_sibling)

Inserts this into the child widget list of parent.

It will be placed before next_sibling, or at the end if next_sibling is null.

After calling this function, `gtk_widget_get_next_sibling(widget)` will return next_sibling.

If parent is already set as the parent widget of this, this function can also be used to reorder this in the child widget list of parent.

This API is primarily meant for widget implementations; if you are just using a widget, you *must* use its own API for adding children.

this	a `GtkWidget`
parent	the parent `GtkWidget` to insert this into
next_sibling	the new next sibling of this