When the user clicks the action's icon, the popup is shown. When the user clicks anywhere outside the popup, the popup is closed. To close the popup programmatically, call
window.close() from a script running in the popup.
You can define a keyboard shortcut that opens the popup using the special "_execute_browser_action" and "_execute_page_action" shortcuts. See the documentation for the
You can ask the browser to include a stylesheet in your popup that will make it look consistent with the browser's UI. To do this, include
"browser_style": true in your
browser_action or page_action key.
Popups have a Content Security Policy that restricts the sources from which they can load resources, and disallows some unsafe practices such as the use of
eval(). See Content Security Policy for more details on this.
Popups resize automatically to fit their content. The algorithm for this may differ from one browser to another.
In Firefox, the size is calculated just before the popup is shown, and at most 10 times per second after DOM mutations. For strict mode documents, the size is calculated based on the layout size of the
<body> element. For quirks mode, it's the
<html> element. Firefox calculates the preferred width of the contents of that element, reflows it to that width, and then resizes so there's no vertical scrolling. It will at most grow to a size of 800x600px if that fits on the user's screen. If the user has moved the popup's associated action to the menu's panel, then the popup appears inside the menu's panel and is given a fixed width.