What does it mean if you have the validation message:
Following actions will not be executed because the page is not opened in a new window as in picture below ?
Answer: If you are using the NavigateToPage action and the Open in New Window is not checked, then all actions (numbered 1 and 2 in the picture) that are after the actions NavigateToPage in the designer won`t be executed.
The technical reason behind it is when you navigate to a different page, not using ‘Open in New Window’, the browser immediately navigates away and all executions stop immediately on the actual page.
The browser navigates to the specified page irrespective of whether the script still has other actions to execute or not, i.e. if actions follow your NavigateToPage, those actions are not going to be executed and therefore are useless.
If you want to execute actions following (in this case, numbered 1 and 2 ) the NavigateToPage action, check the Open in New Window checkbox. This will open the page in a new window.