Please describe the problem:
In the Gaussian blur calculation, it seems that other color values than those in the color channels are used.

Steps to reproduce:
1.Start Gimp
2.Create a new empty transparent image with 400x400 size
3.Select the circle selection tool and drag out a circle in the middle of the image with a size of 100x100 pixels
4.Set background color to white if it is not already white
5.Fill the circle with the background color
6.Remove the selection
7.Run a Gaussian blur with a radius of 50x50 pixels on the entire image
8.Create a new empty transparent layer and place it below the first one
9.Select the new layer
10.Select everything
11.Fill selection with background color


Actual results:
You get a white image with a smooth gray circle on. The Gaussian blur filter does this even if there are no dark pixels in the image. If you after creating the image fill it with white and clear it, you can verify that the transparent pixels are indeed white by using the eraser in the anti-erase mode. Still, the dark areas appear after running the Gaussian blur filter.

Expected results:
I expect to get a completely white image since only white pixels are processed.

Does this happen every time?
Yes

Other information:
I use the Windows version of Gimp.