Mk, well if you know about the coding to make your mane "solid" then I'll try to guide you through the rest.
First, when making the mane, you need to open the "fmanemask" png, which looks like this:
You'll probably have to right click and select "View Image" to see it.
Then, open the "fmaneshade" png as well. It looks like this:
IF YOU ALREADY MADE A MANE, OPEN THAT INSTEAD OF THIS FILE.
Now, on your fmanemask (the black one) you will want to use the Colour Select tool in GIMP (or Magic Wand tool in PS) to click on the transparent area (the grey checkerboard).
Then, under the "Select" tab, choose "Invert Selection".
Now go to your fmaneshade (the white, hair like image) and copy it.
Return to the fmanemask (black one) and click "Paste Into".
Now, under the "Layer" tab, you can select "Anchor Layer"
Back under "Select" tab, you can click "Select None"
Save the final image (it should look like the white hair image, but with transparent triangles on the bottom, like the black one) as "preset_(Number)mane.png"
Note: This isn't for the model, I'm assuming that you want to know how to get rid of this:
And make it into this:
Pictures aren't mine.
