While posting stuff at the forum at forum.howstuffworks.com I noticed that the image markup tag doesn't work if the image is a PNG.
I downloaded a copy of the demo to see how easy it would be to add PNG and other types to the image markup tag.
I found the line that needed to be changed is (in the demo of UBBThreads) is 463:

code:

---

460:    // ---------------------
461:    // Convert image markup 
462:       if ($config[allowimages]) {
463:          $Body = eregi_replace("\[$lang[TEXT_IMAGE]\]http([^\[]*)(.gif|.jpg)\[/$lang[TEXT_IMAGE]\]","<img src=\"http\1\2\">",$Body);
464:       }

---

I added changed it to:

code:

---

463:          $Body = eregi_replace("\[$lang[TEXT_IMAGE]\]http([^\[]*)(.gif|.jpg|.png)\[/$lang[TEXT_IMAGE]\]","<img src=\"http\1\2\">",$Body);

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in my demo and it still worked and now you can use the image markup with PNGs

Just thought you might want to add that image type to the forum. Allowing .jpg to be spelled as .jpeg might also be another good addition.