How to open file using TextMate with new tab
Solution 1:
I am a novice with Textmate2 but have found when opening a file via the TextMate File Browser it open files in tabs. Go to View->Show File Browser.
Hope this helps.
Solution 2:
If you are using TextMate without the internal project functionality you can set your home directory or / as project folder.
Go to the Project folder (Shift + CMD + P) drop down the list and choose your home directory. Then drop down again and choose Use "MyName" as Project Folder. As @Tony has stated in his answer, all files udner the project dir are opened in tabs by default.
It works for TextMate version 2.0-alpha.9475.
Solution 3:
Also a bit of a work around. After opening several windows with text mate you can go to the menu bar Window > Merge All Windows
I also have a keyboard shortcut set up to quickly access the menu bar. This allows me to do this pretty easily and without a mouse.