See https://bugzilla.mozilla.org/show_bug.cgi?id=565541 - this was an intentional change

With regards the resizing of the browser window using Javascript, I need to add that I use my own webpage as a template and the Javascript allowed me to move the window exactly where I wanted it on my screen. Now that this no longer works I end up moving the window manually. What else can I do to make this window resize work?

There are still possibilities to move and resize a window with JavaScript, but they aren't straightforward.
It seems to be possible to do that with code in the Scratchpad (Shift+F4) if a chrome XUL window like about:addons (chrome://mozapps/content/extensions/extensions.xul) or about:config is currently selected to get the required permissions.

See also:

• [/questions/880032]
• [/questions/893034]

• http://kb.mozillazine.org/Resizing_oversize_window

Thanks cor-el, but not being computer literate I do not understand what you mean; neither do I understand any of the responses posted under http://kb.mozillazine.org/Resizing_oversize_window What annoys me intensely is that there is an existing option to tick the box to a) "Enable JavaScript" and within that to b) "Move or resize existing windows". What is the point of those tick boxes? Do not mean to waste your or anyone else's time, but am ready to leave FF for just that simple problem. The way in which I open FF is such that I use an internal own-design web page with positions itself exactly where I want it on my large screen. This option has now been removed by FF; it works fine in IE. Thanks to all for trying to sort this out, it is a FF problem that can surely be sorted?

The simple answer is the moveTo and resizeTo no longer work for the main window and you can only do that via a tab that has an XUL page opened in that tab, so you will have to open such a page and switch to that tab if you want to use JavaScript to move or resize that window. Then you can run such code in the Scratchpad while that tab is selected. Otherwise you need to open a new window via window.open() and run the code in that window.