Use rather than overwrite user specified PopupBorderColor
Use rather than overwrite user specified PopupBorderColor

- Issue MatterHackers/MCCentral#3735
Setting border colors on popup menus has no effect

jlewin/MatterControl,larsbrubaker/MatterControl,larsbrubaker/MatterControl,mmoening/MatterControl,unlimitedbacon/MatterControl,unlimitedbacon/MatterControl,unlimitedbacon/MatterControl,jlewin/MatterControl,larsbrubaker/MatterControl,jlewin/MatterControl,jlewin/MatterControl,unlimitedbacon/MatterControl,larsbrubaker/MatterControl,mmoening/MatterControl,mmoening/MatterControl