Not sure which component this bug belongs to. Different themes can washout the icons on the toolbar so they are invisible or difficult to see. The effect seems to switch between Linux and Windows. Icons are invisible on Ubuntu-Gnome 16.04 x64 in these themes: Default White Balance Icons are invisible on Windows 10 x64 in these themes: Black Body ColorContrast DarkRoom GrayCard LowKey ShadeOfGray SunsetColor The white color icons on the Linux themes (above) and the gray color icons on the Windows themes (also above) do not seem to have enough contrast between the background colors and the icons themselves.
The problem is that icon-sets are not linked to theme, while obviously it is important that their respective color schemes are compatible to get enough contrast such that they are visible. Thus I believe this is a duplicate of #374091 and marked it as such. Please protest and clarify if you think it is not and it will be reconsidered. *** This bug has been marked as a duplicate of bug 374091 ***
Yes, you are correct. I apologize for not having found the original bug and subsequent workaround.
Fixed with #374091