I haven't used Arduino IDE on my main win 10 computer for a while but today I found the font to be different. My Python 3.5 has switched into some Chinese font. It took me a while to find out which font Python IDE comes in default and I switched back. But Arduino IDE has nowhere to specify fonts. There are a number of fonts in the included Java but the only option for font is language, not font.
Thanks for Making Arduino Great Again! LOL
On my arduino 1.6.x, which stores preferences under an arduino15 folder, the font was Monospaced,plain,12. It looked weird. On my arduino 1.0.6, which stores preferences under an arduino folder, the font was also Monospaced,plain,12. It looked like what I'm used to.
After I changed 1.6.x preference to use Consolas,plain,12, I felt it was a slight upgrade since it looks like a vector font, instead of the older more pixelated font.
Glad I was able to help. I just switched to Consolas in the Arduino IDE recently and I found it to be a big improvement. With the default font a lowercase l and the number one looked identical and there was not an obvious difference between an upper case o and a zero; not a good situation for programming! I've now started using Consolas throughout all my software for consistency.
It's very strange but I feel uncomfortable if the font changes. Python uses Courier New, which has the same 1-l problem but not the 0O problem. Anyway, when that font changed into Chinese (it has a subset that includes all English letters) last week, I had trouble focusing on the code. But switching to Consolas on Python didn't create such distraction. Maybe it is a glyph aspect ratio change that made me uncomfortable, not the exact font face details. Both Courier New and Consolas are wider than that Chinese font.