Change caret for any textbox any windows

[suntisuka]

Hello expert,

I want to write function that change caret for any textbox/combobox in any windows. I never write Windows Programming before. After trying many hours, I found code that close to my need from the example of   _WinAPI_CreateCaret function   in AutoIt help file. It captures WM_COMMAND (I don't know what is it) and changes caret. But this example change only caret in its own form, not for all windows. Could you please guide me how to do what I need.

Thanks in advanced.
Suntisuk