Under Windows and Linux, horizontal scroll buttons are automatically added when a PanelGadget has too many tabs to fit the space allotted. Under OSX, the tabs are centered with those to the extreme left and right invisible. I understand that this is an issue with the OSX API.
If possible, adding an optional parameter to suppress drawing of the tabs would allow us to simulate scrollable tabs using ButtonGadgets or even select panels using OptionGadgets.