Second Window With New Sketch

I often need multiple IDE instances open with several Arduinos boards, monitors, and comports. That all works fine. With IDE 1.6.5-rc5, a new sketch replaced the one shown at startup, which I prefer. Versions beyond that now have a different behavior. Opening a second sketch adds a new window and keeps the original. With three instances, I now have six windows. This is causing problems in that editing and uploading is not always the sketch version I expect.

Question: Is there a way to prevent the IDE, V1.6.13, from opening a second window but use the new sketch in place of the original, like V1.6.5-rc5?

Arctic_Eddie: With three instances, I now have six windows.

By this do you mean that when you open a second instance it opens a window for each of the open windows in the other instance? I also find that very annoying and have never experienced anything like it with any other software. I reported it some time ago: https://github.com/arduino/Arduino/issues/3439 But it was closed as "Invalid" by the developer. I would expect that opening a new instance should just load a single window, any other behavior seems to clearly be a bug.

When you open a new instance, the default sketch is the one present when the previous instance was closed. If you open three instances in sequence then they will all have the same sketch. However, if you open another sketch in any of the three instances, the present sketch remains and the new one is in a second window of the same instance. If you do all three then you will have six windows. Three will be the original default sketches and the new three will be the ones of your choice. If you want to edit one of the originals then it gets very confusing as to which comport it's attached and which one to save.

I just want a new sketch that's opened to replace the original and appear in the same window. V1.6.5 is apparently the last IDE that had this behavior.