selenium: is the first window handle always the main window?

Question

Is the first window guaranteed to be the main window? Or is the order random and inconsistent?

for (String handle : driver.getWindowHandles()) {
    driver.switchTo().window(handle);
}

I can't find any information about the order of the window handles, just a way to iterate thorugh them all. I am assuming that the first in the list of window handles is going to be the main window.

Answer 1

According to the current WebDriver API Specification:

6.3 Iterating Over Windows

getWindowHandles

An array containing a window handle for every open window in this session. This array of returned strings must contain a handle for every window associated with the browser session and no others. For each returned window handle the javascript expression "window.top.closed" (or equivalent) must evaluate to false at the time the command is being executed.

The ordering of the array elements is not defined, but may be determined by iterating over each top level browser window and returning the tabs within that window before iterating over the tabs of the next top level browser window.

In short, no - there is no guaranteed order.