there is no concept of 'main'.. there is only the current window and the original window in the current region.

when you pip swap, you request the original window from the specified region. when that happens, the window you are on will move to that spot.

keep in mind, if you swap 2 windows.. then go to an unrelated window and swap with a 4th... then go back to the 1st.. and swap the 5th.. it'll be confusing.

personally, i only swap my primary window with the ones i want. i don't swap the others between themselves