1. A computer-readable storage medium containing computer-executable instructions which when executed by a computer perform the steps for checking a sequence of input characters, the steps comprising: determining whether a sequence checking feature operatively associated with a state transition table, containing allowable sequences of characters based on the rules of a selected language, is enabled, the sequence checking feature being set to operate by a registry entry setting set in the computer's operating system's registry, the registry entry setting being set in the computer's operating system's registry for each language requiring the sequence checking feature; upon determining that the sequence checking feature is enabled: receiving a first character of the sequence of input characters; receiving a second character of the sequence of input characters; determining whether the sequence of characters belongs to a set of characters comprising a selected language by determining that the state transition table includes a state transition from a first state to a second state, the state transition from the first state to the second state indicating that a sequential order of reception of the first character relative to reception of the second character is consistent with one valid sequence of a plurality of valid sequences of characters based on the rules of the selected language; when the first character and the second character form a valid sequence of characters according to the rules associated with forming a complex character, displaying the complex character formed by a combination of the first character and the second character prior to accepting additional characters for display; and when the first character and the second character do not form the at least one valid sequence of characters according to the rules associated with forming the complex character: displaying the first character, preventing the display of the second character, and requiring receipt of a third character as an alternate character prior to accepting additional characters for display.