A disabled HTML button element should look dimmed, grayed out in Konqueror 4

Expected results: A disabled HTML button element should be very easy to distinguish from an enabled HTML button element. A disabled HTML button element should look dimmed, grayed out.

Example given with 2 input form controls:

The enabled input also displays a light blue outline border when hovering it with the mouse cursor.

Actual results in Konqueror 4.3: there is no visual distinction whatsoever between a disabled HTML button element and an enabled HTML button element.

Reference: disabled: When set for a form control, this boolean attribute disables the control for user input. (...) it cannot receive user input
coming from HTML 4.01, section 17.12.1 Disabled controls

An excellent meta-testcase webpage: Robin Lionheart HTML 4 Conformance test: Forms

This bug has been reported at KDE Bug Tracking System as bug 196816.

Valid HTML 4.01!