Sets watching command line of AutoCAD LT LTCustomizer21 for AutoCAD LT reference manual

ActiveX
    Sub enable_extra_command([enable As Boolean = True], [check_time As Long = 100])
C/C++
    int WINAPI LTC_enable_extra_command(BOOL enable,int check_time=100,HWND hwnd=NULL,unsigned int resID=0);

parameter
enable: If True(TRUE), LTCustomizer21 watches specific string. If you want to disable this function, specifies False(FALSE).
check_time:interval time to watch AutoCAD LT command line (Unit is millisec. Default is 100 millisec.(0.1sec).)
When this value is minus, informs string on command line and history of  comand line string after \n(char(10)) code. Before command line is only 1 command line just before.
hwnd,resID(C/C++ only):window handle and message ID to send to your application. LTCustomizer21 sends string executing PostMessage(hwnd,WM_COMMAND,resID,0);. Gets string using LTC_set_extra_word(), after your application receive a message from LTCustomizer21.

After This function executed(first parameter set True), LTCustomizer21 come to watch command line of AutoCAD LT every definite time. When LTCustomizer21 looked for string which is enclosed with special words(default word is '#'), LTCustomizer21 sends string using OnGetUserDefinedCmd() as event in case of ActiveX. If you use as conventional DLL for C/C++ , call LTC_get_extra_string() to get string.

Other notification messages
1. LTC_CLOSE_ACAD: When AutoCAD LT is terminated.
2. LTC_CHANGED_DWG: When AutoCAD LT changed active DWG name.

When LTC_CLOSE_ACAD is notified, LTCustomizer21 terminated watch of AutoCAD LT commandline. You don't have to execute enable_extra_command(False).
When LTC_CHANGED_DWG is notified, LTCustomizer21 notifies DWG name with this message.