GTK L&F: The font of the text foreground color is not grey and it's light blue color

Testsuite name: Swing manual
Test name(s): Swing_AllComponents/Manual/LAFTests/JTextFieldLAFTest
Product(s) tested:OracleJDK13b25(64bit)/tonga-4.0.2-rc2
OS/architecture:ubuntu19.04-x64
option: -Dswing.defaultlaf=com.sun.java.swing.plaf.gtk.GTKLookAndFeel

Actual behavior:
1.step3:The font of the text foreground color is not grey and it's light blue color.Refer to JTextFieldTest-base13b24.jpg and JTextFieldTest-blue.jpg
2.The test failed as the same issue on ubuntu19.04-x64/OracleJDK13b25 without the option.
3.The test failed as the same issue on ubuntu18.04-x64/OracleJDK13b25 with the same option

Affect test:
Swing_AllComponents/Manual/LAFTests/JPasswordFieldLAFTest
Swing_AllComponents/Manual/LAFTests/JComboBoxLAFTest