ADDITIONAL SYSTEM INFORMATION :
javafx 12
openjdk version "11.0.1" 2018-10-16
OpenJDK Runtime Environment 18.9 (build 11.0.1+13)
OpenJDK 64-Bit Server VM 18.9 (build 11.0.1+13, mixed mode)


A DESCRIPTION OF THE PROBLEM :
This is a regression of https://bugs.openjdk.java.net/browse/JDK-8094344
that appeared in javafx 12


STEPS TO FOLLOW TO REPRODUCE THE PROBLEM :
see sample class in https://bugs.openjdk.java.net/browse/JDK-8094344


---------- BEGIN SOURCE ----------
see sample class in https://bugs.openjdk.java.net/browse/JDK-8094344
---------- END SOURCE ----------

CUSTOMER SUBMITTED WORKAROUND :
explicitely setting the font on the tooltip
   tooltip.setFont(Font.getDefault());

FREQUENCY : always