public final void setMnemonicParsing (boolean value)

taken from field

MnemonicParsing property to enable/disable text parsing. If this is set to true, then the Label text will be parsed to see if it contains the mnemonic parsing character '_'. When a mnemonic is detected the key combination will be determined based on the succeeding character, and the mnemonic added.

The default value for Labeled is false, but it is enabled by default on some Controls.