1. A method of enabling input on a handheld electronic device comprising: detecting an input associated with a selected key; determining a likelihood that the input reflects selection of a diacritic character from a set of one or more diacritic characters associated with the selected key; rendering the set of the one or more diacritic characters when the likelihood meets or exceeds a threshold value following expiration of a first period of time that the selected key is engaged in a press-and-hold operation; and rendering the set of the one or more diacritic characters when the likelihood is below the threshold value following expiration of a second period of time longer than the first period of time, that the selected key is engaged in a press-and-hold operation.