This policy turns off the offer text predictions as I type option. This does not however prevent the user or an application from changing the setting programmatically. The offer text predictions as I type option controls whether or not text prediction suggestions will be presented to the user on the on-screen keyboard. If the policy is Enabled then the option will be locked to not offer text predictions. If the policy is Disabled or Not Configured then the user will be free to change the setting according to their preference. Note that the availability and function of this setting is dependent on supported languages being enabled.
Control Panel\Regional and Language Options
At least Windows Vista