Development tools for Zephyr on STM32Workbench for Zephyr: VS Code extension to set up, build, flash and debug Zephyr applications on STM32.Devicetree manager: browse, edit and visualize Zephyr devicetree, STM32CubeMX-like for Zephyr.
Eclipse Luna works best for me in Xubuntu 16.04 64bit. It is possible to have multiple Eclipse installations on your HDD, try an older version of Eclipse.