I have already looked at that.  The button is in the editor and is working fine.  Click on the button, dialogue comes up and if the user had selected an image I can extract the source (and from that my equation Latex code).  All this works.  If the person changes the Latex code in the dialogue, I want to rebuild the image src and replace the src on the selected image in the editor.  This is what I cannot get working.   

 

In addition to the above code (one post up) I have also tried the editor PasteHTML function.  This works fine if the user has not selected an image and I am inserting html for a new image.  This does not work if the user has selected an image and I want to replace the selected image html with a new image html. 

 

To let you know why I am trying to do this, a typical src would be '/Eq?$A^3 sqrt(2)=25$'.  I am only showing the bit between the '$' in the dialogue box and the user will edit this to change the equation.  I then need to replace the original src tag.  Everything is working apart for the very last bit of getting the changed src (or full image html) back into the editor.  The above would generate: