In Sublime Text 2, how do I open new files in a new tab?

When I'm editing with files on the server, and I click to edit them, if I'm editing multiple files (say an HTML file and a CSS file) but they open in new windows, which, on my small laptop display is a little inconvenient.

How do I make it open in a new tab, rather than a new window?

OSX-Only: Add the following to Preferences > Settings - User or ⌘ + , :

"open_files_in_new_window": false

This is the correct syntax i.e. use a comma...

{
	"color_scheme": "Packages/Color Scheme - Default/Monokai.tmTheme",
    "open_files_in_new_window": false
}

Open up your user preferences file

Preferences > Settings - User

Add the following line

"open_files_in_new_window": false

Make sure you place it withint the {}as you may already have some settings in there. Make sure you add the ,after the previous setting.

Example:

{
	"color_scheme": "Packages/Color Scheme - Default/Monokai Bright.tmTheme",
	"font_size": 14.0,
	"open_files_in_new_window": false
}

For Windows users:
By default the above setting value will be true i.e.
"open_files_in_new_window": true

If you are using sidebar then just double click on the file to open it in a new tab.

If the current file is not modified, then by single clicking on a new file, will close the current file and open the new file on the same tab.

I use the sidebar menu. I put the folder holding my file in the sidebar by drag and drop. Search tour file in the menu, then just double click it. This will cause it to display in a tab.