This will be hard because the XCF file format assumes 64x64 tiles. Currently there is no easy way to see the effects of compression or other image saving effects before actually saving and reloading an image. The more that can be done by power-users without having to delve through dialogs the better. This is mostly implemented already. For example, you have a custom palette you like, but you want it to get dark from left to right.
More stuff needs to be triggered via pdb to make thsi a possibilty.
The more value-added utility we can make for Xinput stuff the better. A suggestion from Xach, Perhaps instead of rendering the text and font size exactly, make a bounding box of it, then scale the bounding box as approriate. When the box size is chosen, figure out the best-fit font size and render it. Using X to render text is cheap but nasty. 1.0 iscissors basically dont work though.