Improve mac style rendering of ctkRangeSlider
Improve mac style rendering of ctkRangeSlider

2 problems:
 - An handle was always drawn at minimum position
 - Drawing the second handle was drawing a groove on top of the first.

msmolens/CTK,AndreasFetzer/CTK,151706061/CTK,ddao/CTK,vovythevov/CTK,SINTEFMedtek/CTK,jcfr/CTK,Heather/CTK,naucoin/CTK,commontk/CTK,danielknorr/CTK,SINTEFMedtek/CTK,CJGoch/CTK,Sardge/CTK,mehrtash/CTK,AndreasFetzer/CTK,pieper/CTK,jcfr/CTK,laurennlam/CTK,vovythevov/CTK,commontk/CTK,espakm/CTK,Sardge/CTK,pieper/CTK,151706061/CTK,laurennlam/CTK,naucoin/CTK,ddao/CTK,jcfr/CTK,naucoin/CTK,mehrtash/CTK,mehrtash/CTK,fedorov/CTK,AndreasFetzer/CTK,pieper/CTK,commontk/CTK,msmolens/CTK,sankhesh/CTK,SINTEFMedtek/CTK,rkhlebnikov/CTK,151706061/CTK,rkhlebnikov/CTK,Heather/CTK,danielknorr/CTK,pieper/CTK,151706061/CTK,finetjul/CTK,vovythevov/CTK,msmolens/CTK,finetjul/CTK,rkhlebnikov/CTK,SINTEFMedtek/CTK,jcfr/CTK,CJGoch/CTK,Sardge/CTK,finetjul/CTK,Sardge/CTK,danielknorr/CTK,SINTEFMedtek/CTK,sankhesh/CTK,ddao/CTK,msmolens/CTK,vovythevov/CTK,CJGoch/CTK,espakm/CTK,espakm/CTK,sankhesh/CTK,finetjul/CTK,commontk/CTK,Heather/CTK,mehrtash/CTK,sankhesh/CTK,fedorov/CTK,ddao/CTK,AndreasFetzer/CTK,naucoin/CTK,fedorov/CTK,Heather/CTK,fedorov/CTK,laurennlam/CTK,rkhlebnikov/CTK,espakm/CTK,CJGoch/CTK,laurennlam/CTK,danielknorr/CTK,CJGoch/CTK,151706061/CTK,jcfr/CTK