This bug still exists. I can confirm it.
Edit:
What the bug does:
In the "Animation frames" window all options except "Thumbnail size" are and keep grayed out.
How to repruduce it:
You have to make the "Edit image" window big. If it is, the options will be grayed out if the "Edit image" window is close to the "Animation frames" window. If the "Edit image" window is not big enaugh, the options will not be grayed out, even if the windows are very close to each other.
The bug occured by editing a 800x480 image.
If the "Edit image" window is big...but not too big the options will be grayed out. But if you wait a few seconds after you right clicked the "Animation frames" window they wont be grayed out anymore. So I assume there must be an image (size?) calculation error or something similar.
Oh and I use r146.