I don't know, in fact, I wasn't on my computer when Arduino 1.8.4 crashed for the first time.
Indeed, before the software crashed, the person on my computer told me that the the font size has changed, so I think he has done this keyboard shortcut.
I changed the font size in AppData/Local/Arduino15/preferences.txt (it was set to -397) and It works !
Thank you pert
