Editing existing gradients with GIMP
Editing gradients with two or more segments
Something which took me ages to find out, was changing colours on gradients with two or more segments. It's actually a tooltip in the gradient editor, but I kept missing it. In the end I found it by accident and like anything that is supremely frustrating, when you know how it's done it's really quite simple.
So here it is. Duplicate one of the supplied gradients made up of three segments, I've used the Romanian flag gradient here.
You'll notice that there are black & white triangles below the gradient. The black ones are the beginning and end of each colour segment, slide them from left to right and the colour position changes. Double clicking between one of the black triangles will make the colour above active, so that you can edit it. The active segment is highlighted a darker colour than the other two. I've made the right segment active in the example below.
Right click on the active segment and choose
Left Endpoint's Colour .... The Left Endpoint Colour box will appear, allowing you to type in your new colour.
Repeat the process for the
Right Endpoint's Colour ... to complete the colour change for this segment. In this case from red to green.
Double clicking on the other segments and repeating the above processes will complete your new gradient, which can now be saved for future use.