A couple of times I’ve hit an issue whenever I install NetBeans on Ubuntu.
The fonts in the menu and explorers become bold. This is mostly not an issue, but when you are editing files the font changes from normal to bold so that you know that you have unsaved changes.
This appears to be a bug with the Oracle JDK, but it’s Ubuntu’s fonts that are triggering it. The easiest way to fix this until there is some proper resolution is to run the the following command to remove the fonts.
sudo apt-get remove fonts-unfonts-core
This will remove the fonts causing the issues. Restart NetBeans for the changes to take effect.
See the bug report at NetBeans for more information