It's not completely finished and I will not release it just yet. I still have some small bugs I need to sort out, and as can be seen in the screenshot, I need to draw some icons for the toolbar. But other than that it is fully functional and can generate font images and export their definitions in both Ogre's own fontdef file format, a plain text format and a binary format.
Rectangle textured with the fire effect
It was much simpler to solve than I thought when I started. All that was needed was three textures, two that would hold the fire intensity values and one palette texture. The two textures holding the fire values would alternate between being the target and source. I would read the old values from one texture, and then write the new updated values to the other one, and then at the next frame switch the two. Then when it was time to render the fire effect, I got the fire intensity value from one of the two textures, and then using that value like a texture coordinate in the palette texture to get the right color.