How to modify the font size in the code editors?

You can increase/decrease the font size in code editors using these buttons, on the main toolbar:

You can can also modify the font settings from Window ‣ Preference ‣ General ‣ Appearance ‣ Colors and Fonts. For global settings (used by all editors), select Basic ‣ Text Font and for editor specific settings, select (e , Verilog, VHDL) Language ‣ Editor ‣ Text Font.