I was having a problem with the MCPUK image editor not working, but after a bit of digging I found the the source of the editorFrame.php was returning the image correctly to all the javascript functions but then calling
<span id="imgCanvas" class="crop"><img src="<?php echo MODX_BASE_URL . $imageInfo['src']; ?>" <?php echo $imageInfo['dimensions']; ?> alt="" id="theImage" name="theImage"></span>
when it came to actually displaying the image.
This resulted in the image not being found (that is red cross in IE, blank in Fx and Opera), because the php evaluates to src="/
http://mydomain.com/assets/images/picture.jpg" (extra slash).
On a hunch I added $ to MODX_BASE_URL so it now reads $MODX_BASE_URL, and it now seems to work perfectly. Has this problem occurred for anyone else (i.e. should I file it as a bug) or is it just me?
