Question: I asked [how I can resize the browser window with JavaScript](https://stackoverflow.com/questions/7022787/can-i-resize-the-browser-window-size). Everybody told me not to do it. Why is this a bad practice?

I think sometimes it can be good. For example, I want to show users a tweeting popup page. After a user tweeted, I want to redirect him to twitter main page to let him verify his tweet. But tweeting page is small and main page should be big. In this case, making the browser window bigger seems good for user. Am I wrong? Then how should I do in this case?

**Update**

I think I need to make somethings clear.

1. I also don't want my browser to be resized. Resizing users' browser is usually bad. What I want to know is that there could be some case it can be good.
2. I also don't like popups. But as @zzzBov said, pop-outs are different. That is used in many websites even in Stack Exchange(You can see share buttons under the favorite button). I don't think it would be better if those buttons were jQuery modal dialog.

And, JavaScript `resizeTo` function can resize the browser. When I tested that function, it works well in browsers but Chrome. In Chrome, it works just in popups. I might be wrong, but I guess Chrome team also may thought that the `resizeTo` function would be needed in popups.

**Update2**

Most people just don't want the method `resizeTo` to be used anytime and anywhere. I think if that method were totally evil and useless, the browsers vendors had already disabled that method, but they didn't. 

In Chrome and Opera, the `resizeTo` method is available just in popups, and in Firefox users can disable it manually. I'm sure that one should be very careful when using the method. But I believe this method can be useful in some case.

Answer: 
Many users have multiple windows open at one time (some on multiple screens), and resizing can really mess with the layout. Additionally, most internet use (at least in my personal experience) invloves multiple open tabs. Resizing the browser window will affect not just your application, but the other tabs in the window as well.
Lastly, it's just plain annoying when the browser window suddenly changes on its own.
It's bad practice when your user is human.

When your user is a virtual framebuffer, it's different. In automated testing we often need to work with windows of specific sizes to ensure that elements and events and interactions are being captured and processed in a consistent manner.

It is extremely inconvenient to get the operating system to change resolution on the framebuffer, you have to leave whatever environment you're working and automating in and move down and trigger automatic commands at operating system level. Much better to simply resize the (virtual) browser window and continue.

Problem is, most browsers don't allow this because it interferes with the "user experience". Which means that users are exposed to non-working sites or sites that don't run at unusual screen resolutions / dimensions / ratios.