Builder.addFromString

Parses a string containing a UI definition and merges it with the current contents of builder.

This function is useful if you need to call [gtk.builder.Builder.setCurrentObject] to add user data to callbacks before loading [gtk.builder.Builder] UI. Otherwise, you probably want [gtk.builder.Builder.newFromString] instead.

Upon errors false will be returned and error will be assigned a [glib.error.ErrorWrap] from the GTK_BUILDER_ERROR, G_MARKUP_ERROR or G_VARIANT_PARSE_ERROR domain.

It’s not really reasonable to attempt to handle failures of this call. The only reasonable thing to do when an error is detected is to call g_error().