This is textbox code I wrote a while ago and often use in various things, with text wrapping and overflow detection.

#define TEXTBOX_ACCEPT_OVERFLOW		0

#define TEXTBOX_MINIMUM_LINES		0

#define TEXTBOX_PRINT_DELAY		5

#define TEXTBOX_FONT_HANDLE		font_main



int default_textbox_x = 5;

int default_textbox_y = 5;

int default_textbox_width = ImageWidth(screen) - 10;

int default_textbox_maxlines = 2;



int textbox_x, textbox_y, textbox_width, textbox_maxlines, textbox_active;



void AlterTextBox(int tb_x1, int tb_y1, int tb_width, int tb_maxlines)

{

	textbox_x = tb_x1;

	textbox_y = tb_y1;

	textbox_width = tb_width;

	textbox_maxlines = tb_maxlines;

}



void DefaultTextBox()

{

	AlterTextBox(default_textbox_x, 

			default_textbox_y, 

			default_textbox_width, 

			default_textbox_maxlines);

}



void TextBox(string tb_text)

{

	int tb_font = TEXTBOX_FONT_HANDLE;

	

	string tb_cur_text;

	

	// Find the width and subract some. Because there is padding on all sides.

	tb_text = WrapText(tb_font, tb_text, textbox_width - 16);

	

	tb_cur_text = tb_text;

	

	if (TEXTBOX_ACCEPT_OVERFLOW)

	{

		while (TokenCount(tb_text, chr('\n')) > 0)

		{

			if (TokenCount(tb_text, chr('\n')) + 1 > textbox_maxlines)

			{

				tb_cur_text = TokenLeft(tb_text, chr('\n'), textbox_maxlines);

				//tb_cur_text = right(tb_cur_text, len(tb_cur_text) - 1);

				tb_text = TokenRight(tb_text, chr('\n'), textbox_maxlines);

				if (!len(tb_cur_text))

				{

					tb_cur_text = tb_text;

					tb_text = "";

				}

			}

			else

			{

				tb_cur_text = tb_text;

				tb_text = "";

			}

			TextBoxHandler(tb_font, textbox_x, textbox_y, textbox_width, tb_cur_text, 1);

		}

	}

	else

	{

		TextBoxHandler(tb_font, textbox_x, textbox_y, textbox_width, tb_cur_text, 1);

	}

}





void TextBoxHandler(int tb_font, int tb_x1, int tb_y1, int tb_width, string tb_text, int tb_more)

// Pass: The font to use, the coordinates of the textbox, the

// prewrapped string to display, whether or not to draw a bobbing

// arrow at the bottom.

// Return: void

// Assumes: The font is valid

{

	int done;

	int box_time;

	int mid_offset, line_offset, line_count;

	string mid_text, line_text;

	

	textbox_active = 1;

	

	line_count = max(TokenCount(tb_text, chr(10)), TEXTBOX_MINIMUM_LINES);

	Unpress(1);

	box_time = systemtime + (len(tb_text) * TEXTBOX_PRINT_DELAY);

	

	while (!done)

	{

		RectFill(0, 0, ImageWidth(screen), ImageHeight(screen), RGB(255, 0, 0), screen);

		Render();

		// Draw our textbox window.

		DrawWindow(tb_x1, tb_y1, tb_x1 + tb_width, tb_y1 + 16 + (line_count  * FontHeight(tb_font)), screen);

		

		// Draw the "More text" arrow.

/*

		if (tb_more)

		{

			TBlit(tb_x1 + tb_width - 16,

				tb_y1 + (sin(systemtime * 2) * 4 >> 16) + 6 + (line_count  * FontHeight(tb_font)),

				img_arrow_down, screen);

		}

*/	

		// Blit the lines of text.

		PrintString(tb_x1 + 8, tb_y1 + 8, screen, tb_font, mid_text);

		ShowPage();

		

		// Increment the length our text midsection.

		if (mid_offset < len(tb_text))

		{

			mid_offset = len(tb_text) - ((box_time - systemtime) / TEXTBOX_PRINT_DELAY);

			if (mid_offset > len(tb_text)) mid_offset = len(tb_text);

		}

		

		mid_text = left(tb_text, mid_offset);

		

		// Hitting B1 causes all text to appear.

		if (b1 && mid_offset < len(tb_text))

		{

			Unpress(1);

			mid_offset = len(tb_text);

		}

		// Hitting B1 can also cause us to exit this textbox loop.

		else if (b1 && mid_offset == len(tb_text))

		{

			Unpress(1);

			done = 1;

		}

	}

	

	textbox_active = 0;

}

It makes reference to a builtin function called WrapText(), TokenLeft() and TokenRight(), and an updated PrintString which accepts line breaks, which can be found in the SVN build. (Username: anonymous, Password: anonymous) Also, replace DrawWindow with your own window drawing routine. This might be a little more than you need, so maybe just use it as a reference or tweak it to your requirements.

Also, this code was copypasta from a larger source file of mine, I hope all the requirements are there. Oh yeah, and call DefaultTextbox() in your Autoexec().

Basically, it checks to see if the scrolling text has reached the end, and, if it hasn't reached the end yet, it uses a timestamp and divides that by the delay for each letter.

When the TextboxHandler is called initially, box_time is set to the current systemtime plus the time that each letter in the text will take to print. To get how much time has passed since the textbox started and have it be consistent across machines, (box_time - systemtime) is used, which will count up automatically as the engine loops along.

If you don't use timestamps, the only other good way to get timing to be the same on every machine is to use frame limiting. But that's a bit trickier, and little unnecessary if you only need it for the textbox, especially if you don't care about the frames in between you potentially miss. I suppose there's also HookTimer(), but that means a lot of ugly setup in advance, and once again does unnecessary extra work between drawn frames. Anyway, Verge's timing functionality is useful and important stuff.

Yeah, er, drawing stuff with font subsets would be a pain at the moment.