An uncomfortable situation for beginners (and for me!)

If the menu function “Open file” is used, the new file exactly covers the old one. If the serial monitor is open in the old sketch - which is now invisible - no upload is possible! It took me some time to find this.

Interesting! I am still using 1.8.13, and New opens a much smaller box.
I wonder if that is adjustable under Preferences, or manually in the Preferences.txt file?

I’m talking about Arduino 2.0 IDE!

Yes it is, but he is talking about 2.0, but it is possible in 1.8

The classic Arduino IDE 1.8.x can do better. It doesn’t cover a previous sketch. You can see very clearly that 2 (or more) sketches are now open.