Win32WarningHandler and Win32ErrorHandler open a message window by default. If
TIF_PLATFORM_CONSOLE is defined at compile time, messages are sent to stderr
instead of using a message window.

For console applications the current default is not optimal. Imagine software
like Tesseract doing batch processing (OCR) of image files. Then each TIFF file
with some vendor specific field will stop the batch process and show a message
window requiring user interaction.

The default message handlers could check whether there is a console and use a
message window only for GUI applications started without a console.

Sample code:

static int isGuiApp(void)
{
    return GetStdHandle(STD_ERROR_HANDLE) == NULL;
}

...

if (isGuiApp()) {
    // Output to message window.
    ...
} else {
    // Output to stderr.
    ...
}