I want to be able to move the current tab from the window (with other tabs) to a new window, in the foreground, keeping all other tabs open. I'm using Google Chrome, always up to date, on Ubuntu 14.04.2.
I'm happy for a script / extension / similar.
Bear in mind I have a number of windows open (maybe 3 or 4).
It can't be closing and reopening the tab because I may have unsaved details (e.g. I'm taking a screenshot of the typed content).
Use Tab To Window extension of chrome. it will provide you several shortcuts to manage your tabs.
For example, use Alt+Shift+X to move the active tab to a new window.
The shortcuts are customisable.
In case someone is interested in a current solution without extensions:
If you just start typing the name of the website you want to access or highlight the URL and press Shift+Return, a new detached window will open.
Personally I can't live without Vimium as it lets me do so much more than just move tabs.
You can easily open a tab into a new window with W or you can search across all your open tabs (in all windows) with T or open a url from your history with O. If you were editing text in an input field you may need to hit Esc first to "unselect" the field, but that is common with "modal" editors like Vim which Vimium borrows many of its ideas and key mappings from.
A new tab is just a t away as well.
Sadly it doesn't have any direct "send tab to a specific window" options like Tab to Window (or at least the version I used to use on Firefox allowed that), but it sounds like you don't need that.
For actually moving tabs to organize them I use the extension Tabs Outliner which works great and lets you "tag" windows and tabs with notes, and the BEST feature is that you can simply hit Ctrl+s to save out the entire list of tabs to send via email or backup with Dropbox/Drive/etc.
There is an extension called Tab Manager
Install it and easily you can do what you want
When you click on + as shown in the picture this will detach the current tab to a new window
Press F6 which selects the search/url field then press it again which would select the tab, then press shift+F10 (which is right click) from there select the second option "move tab to new window" and from there select "new window".