# Controls user defined functions Reference

Below is a complete list of the user defined functions available in AutoIt. Click on a user defined function name for a detailed description.

When using them you need to add a #include <WinAPISys.au3>.

User Defined Function | Description
--- | ---
_WinAPI_GetEffectiveClientRect | Calculates the dimensions of a rectangle in the client area that contains all the specified controls
_WinAPI_GetMUILanguage | Gets the language currently in use by the common controls for a particular process
_WinAPI_InitMUILanguage | Enables an application to specify a language to be used with the common controls that is different from the system language