Build with and for GMS 1.4. As title says, it's a simple way for user to enter a string. For name input, player's information, custom name, etc... Simply use:
scr_call_input(x, y, id, max_string_length)
X, Y is where you want it to be displayed. You limit the string length then press enter. Store that string into the variable you need. Can be implemented easily in any games. As always, it's well commented.