Creates a new Label, containing the text in
If characters in
str are preceded by an underscore, they are underlined. If you need a literal underscore character in a label,
use '__' (two underscores). The first underlined character represents a keyboard accelerator called a mnemonic. The mnemonic key can be used to
activate another widget, chosen automatically, or explicitly using
If set_mnemonic_widget is not called, then the first activatable ancestor of the Label will be chosen as the mnemonic widget. For instance, if the label is inside a button or menu item, the button or menu item will automatically become the mnemonic widget and be activated by the mnemonic.
The text of the label, with an underscore in front of the mnemonic character
the new Label