xfa.host.openList

Hi everyone.  I am using this in the "enter" event for my dropdown list:

xfa.host.openList("Dropdown2");

When I tab onto that field, the list does open but only for a quick second and then closes.  Does anyone know how I can make this list stay open?

Putting that code in the MouseEnter event works too but that will not work if I'm using "tab".

Thanks so much in advance!