You have to create a basic rounded knob widget, most of logic needed for it is already supplied by BSlider, and you have to follow it's interface, so your work will be concerned in reworking the drawing part (ie changing the drawing of the slider to be a knob).

Source code :

http://haiku.it.su.se:8180/source/xref/src/kits/interface/Slider.cpp

http://haiku.it.su.se:8180/source/xref/headers/os/interface/Slider.h

Those requirements should be met :

• The code shall conform to the Haiku Coding Guidelines
• You have to use an appropriate widgets naming (ask your mentor).
• Your widget shall use the haiku's layout kit.

Your mentors are always here for more informations.

If the task will be more big than expected, you can ask your mentors to create a second part of the task, if needed.