(1) kcontrol has nothing in it (the screenshot is taken in a KDE session, btw).
(2) Note how hinting is not correctly used -- for example the menu of kcontrol. Notice how the i and l letters (lowercase L) are thickened (try zooming a lot) and look dirty or blurry. Compare with the piece of the Gimp window visible in the background, where all vertical lines are very clean.
This is a screenshot showing both issues:
(1) kcontrol has nothing in it (the screenshot is taken in a KDE session, btw).
(2) Note how hinting is not correctly used -- for example the menu of kcontrol. Notice how the i and l letters (lowercase L) are thickened (try zooming a lot) and look dirty or blurry. Compare with the piece of the Gimp window visible in the background, where all vertical lines are very clean.