keyboard_check_direct(key);
| Argument | Description | 
|---|---|
| key | The key to check the down state of. | 
Returns: Boolean
This function will return true if the key with the particular keycode is pressed, or false if it is not, by checking the hardware directly. It allows for a few more checks, in particular you can use 
keycodes vk_lshift, vk_lcontrol, vk_lalt, vk_rshift, vk_rcontrol and vk_ralt to check whether the left or right shift, control or alt key is pressed.
NOTE: This function is only available for the standard Windows target and the result is independent of which application has focus.
if keyboard_check_direct(vk_ralt) || keyboard_check_direct(vk_lalt) 
   {
   crouch = true;
   }
The above code will check to see if either the left or right alt keys have been pressed, and if they have it sets the variable "crouch" to true.