Color problems [was: Re: KDElibs: KSystemTray: On window close dialog]

Olaf Jan Schmidt ojschmidt at
Tue Sep 28 10:23:26 BST 2004

Hash: SHA1

[Sébastien Laoût "\[temporar\]", Dienstag, 28. September 2004 01:06]
> - NOT changed color from red to highlighted one because this is less
>   visible: there are a lot less contrasts

I disagree. Hardcoding colors is an accessibility No-No.

In this case, it has the following problems:

1. What if you have a red background in kicker?
2. What if you have a green background and are color-blind?

We have a similar problem in kdm, where red color is used for the warning 
text if Caps Lock is activated. At one point I had problems seeing it on 
my computer, I defined a red background color for the user root, and it 
was also used in kdm. (It was KDE 3.1, maybe the color schemes have been 
seperated in the meantime, but the point remains.)

Would it be possible to add a "Warning Color" to the color schemes for KDE 
3.4, or would this break binary compatibility? Otherwise a solution might 
be to use two colors instead of only red.

There are similar problems with hardcoded black. KDE is currently hardly 
usable for people who need white text on black background because of low 
vision. This needs a lot of independent fixes in KDE. I will discribe 
more problems later and only mention two problems here, because they are 

None of the styles works correctrly using a white on black color scheme.  
We either need to add a style frame color to the color scheme, or the 
styles need to check for the background color and optionally use white 
instead. At least the default style for KDE 3.4 should be fixed, but it 
would be better if none of the styles had this bug.

A related problem needs to be fixed in Qt: The 3D effect currently only 
really works if the background color is light. If the background color is 
black, both 3D effect colors are also black, meaning that frames are 

The currently algorithm for both shadow color and light effect color is 
something like:
brightness = factor * brightness of background color

This can be fixed by using an inverted algorithm for the light effect 
darkness = factor * darkness of background color


- -- 
Olaf Jan Schmidt, KDE Accessibility Project
KDEAP co-maintainer, maintainer of

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