system.gui.showTouchscreenKeyboard(initialText [, fontSize] [, passwordMode])
String initialText - The text to start the on-screen keyboard with.
int fontSize - The font size to display in the keyboard. [optional]
boolean passwordMode - True (1) to activate password mode, where the text entered isn't echoed back clear-text. [optional]
String - The text that was "typed" in the on-screen keyboard.