I get multiple instances of IDE also. Beyond that, I have to check the board selection, programmer, port and ISP in each instance of the open sketch. I use a lot of ATTinys, mostly X4 and X5, plus the ArduinoISP. To load the ArduinoISP, I need to reset the board to Uno, load the ISP sketch, then select an ATTiny sketch, which pops up in a new window. Then change the board to ATTiny85 and load the sketch. Even though I selected Uno on the first sketch, the board change on the second sketch affects the first. If I go back to the first sketch, I have to change the board back to Uno.
I'd like to see the board selection. programmer and port tied to the sketch, rather than a global set of variables.
Jim