Hope I'm no necroing here, but in a few of my games I use an active shape object(for the GUI), an active picure object (for the avatar), and character image object (the text). You can change the color and opacity of the active shape object at runtime. The active picture object can swap avatar images at runtime, too. The character image object can be swapped with any bitmap font extension.
You can use a couple more extensions to basically create a script interpreter that loads an external game script file like this:
[gametextInts]
NoOfValues=0
Base=0
[gametextStrings]
NoOfStrings=1024
Base=0
0=01Welcome to this game.
1=01As of right now, there's no title for this game. Odd, since how could one be building an entire engine without having any idea what to make the game about.
2=02I mean, so far there's no hero. What kind of game is this when there isn't even a hero. Pretty lame, if you ask me.
3=02No graphics, no enemies, no music. What qualifies this as a game at all?
4=03Nothing! This simply is not a game. Happy now? You've gone and upset the developer.
5=01Shame on you.
6=02Oh, hello there. As you can tell by your surroundings, you've caught me a bit off-guard. I'm afraid I'm not really prepared to prompt you with text.
7=04I hope you'll understand. I don't mean to be rude, but I'm not even a sign yet. Just a lowly ground tile that triggers a dialog event.
8=35If you look to your left, you'll see my brother the orange tile. He's kind of inconsiderate and foreboding. All the other event triggers think he's full of himself.
9=01Don't bother triggering his event dialog unless you want to see seperate event triggers pull text from seperate ini entries in the same file.
10=02Ini entries? Files? I'm not quite sure what those are, but the programmer asked me to read from this script. He said you'd understand.
11=01Am I still talking? Probably.
12=08I'm STILL talking. This should not be happening.
You can use the global store x extension to load a list of strings from an ini file in the game directory. You can call specific strings right from it. The two numbers at the very beginning of each string can be pulled with Val$ and Left$ string manipulation. They control which avatar loads beside the text - just keep a bunch of images titled 01-99 in a local game directory. You can load the Right$(length of string)-2 into the character image extension once you have a font configured.
All you need to do at that point is create, reposition, or change visibility to make the dialog system disappear off screen and reappear on-screen, create a group of events that freeze on-screen enemies and players triggered by an object flag; Turn it on and everything freezes, the dialog appears, the string is requested from the global store x object and external INI. The left two characters of the string gets converted into a value and the active picture object loads a file like 05.png from a local folder. The remainder of the string gets loaded into the character image object as text. If the flag is still on while the user pushes a keyboard key, just grab the next string and display it. If the user pushes the same button while the flag is off, have it make all dialog objects invisible (move them, destroy them, whatever).
I like to add a couple of buttons on the active shape object that control the whole dialogue's positioning on-screen (so it can appear at the top or bottom of the frame. At one point, I had a dialog system that ran just by supplying a beginning line and end line of the script. Once it reached the last line, it would "unpause" the characters and kill the dialog system objects entirely. I was able to allow in-game events change the conversations each of the NPCs had with the main... kinda like a reputation system. Still trying to figure out a convieniant way to build options into this sort of engine.
Active shape > active object where simple guis are concerned. Opacity at runtime without much resource impact for the win.
