Opens the given URL. In UNIX executes Netscape, Safari (MacOS) or Firefox (in Linux) passing the desired URL as a parameter. In Windows executes the shell "open" operation on the given URL.
In UNIX you can change the used browser setting the environment variable IUP_HELPAPP or using the global attribute "HELPAPP".
It is a non synchronous operation, i.e. the function will return just after execute the command and it will not wait for its result.
Since IUP 3.17, it will use the IupExecute function.
int IupHelp(const char* url); [in C] iup.Help(url: string) -> (ret: number) [in Lua]
url: may be any kind of address accepted by the Browser, that is, it can include 'http://', or be just a file name, etc.
Returns: 1 if successful, -1 if failed. In Windows can return -2 if file not found.